AI Trajectory

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Seq	Timestamp	Type	Name	Duration
0/0	2026/09/07 22:10	flow	patch-triage	2m Args: null Results: { "EnableConfigs": [ "IP_VS", "NETFILTER", "INET" ], "FocusSymbols": [ "ip_vs_dest_update_overload", "ip_vs_bind_dest", "ip_vs_unbind_dest", "__ip_vs_update_dest", "ip_vs_edit_dest", "ip_vs_add_dest", "ip_vs_rr_schedule", "ip_vs_wrr_schedule", "ip_vs_wlc_schedule", "ip_vs_lc_schedule", "ip_vs_fo_schedule", "ip_vs_ovf_schedule", "ip_vs_twos_schedule" ], "KMSANReasoning": "The patch reorganizes fields in `struct ip_vs_dest` for better cacheline utilization and refactors the destination overload status tracking to use `l_threshold_val` / `u_threshold_val` instead of `dest-\u003eflags` with `IP_VS_DEST_F_OVERLOAD`.\n\nAll `struct ip_vs_dest` instances are zero-allocated with `kzalloc_obj()` and their threshold fields are properly initialized upon creation. The structure itself is not copied to userspace as a raw blob; userspace queries serialize individual fields or use zeroed intermediate structures (`memset` in `__ip_vs_get_dest_entries` and individual Netlink attributes in `ip_vs_genl_fill_dest`). No uninitialized memory is read, copied to userspace, or branched upon.\n\nBecause the changes introduce no uninitialized memory risks, a dedicated KMSAN fuzzing session is not warranted. Standard KASAN fuzzing is sufficient.", "NeedsKMSAN": false, "Reasoning": "The patch modifies the destination overload tracking logic and destination structure layout in the IPVS (IP Virtual Server) subsystem. It updates connection binding and unbinding thresholds, control plane destination updates, and scheduler overload evaluation across IPVS algorithms. These are reachable, executable network paths that should be fuzzed for race conditions, arithmetic or state handling bugs, and threshold edge cases.", "WorthFuzzing": true }
1/1	2026/09/07 22:10	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit a029c18539e2bd4393bb8736df0003e422cb7c9b\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Mon Sep 7 22:10:16 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/include/net/ip_vs.h b/include/net/ip_vs.h\nindex 32fde731bceb7..9a83bff32569d 100644\n--- a/include/net/ip_vs.h\n+++ b/include/net/ip_vs.h\n@@ -36,9 +36,6 @@\n #define IP_VS_HDR_INVERSE\t1\n #define IP_VS_HDR_ICMP\t\t2\n \n-/* Destination Server Flags /\n-#define IP_VS_DEST_F_OVERLOAD\t0x0002\t\t/ server is overloaded /\n-\n / Destination Server Config Flags /\n #define IP_VS_DEST_CF_AVAILABLE\t0x0001\t\t/ server is available /\n \n@@ -973,32 +970,43 @@ struct ip_vs_dest_dst {\n and so on.\n /\n struct ip_vs_dest {\n+\t/ Cacheline for hash table nodes - read-mostly /\n+\n \tstruct list_head\tn_list; / for the dests in the service /\n \tstruct hlist_node\td_list; / for table with all the dests /\n \n-\tu16\t\t\taf;\t\t/ address family /\n-\t__be16\t\t\tport;\t\t/ port number of the server /\n-\tunion nf_inet_addr\taddr;\t\t/ IP address of the server /\n-\tvolatile unsigned int\tflags;\t\t/ dest status flags /\n-\tatomic_t\t\tconn_flags;\t/ flags to copy to conn /\n \tatomic_t\t\tweight;\t\t/ server weight /\n-\tunsigned long\t\tcflags;\t\t/ config flags /\n \tatomic_t\t\tlast_weight;\t/ server latest weight /\n+\n+\t/ connection thresholds /\n+\tu32\t\t\tl_threshold_val;/ used lower threshold /\n+\tu32\t\t\tu_threshold_val;/ used upper threshold /\n+\t/ 32/48 /\n+\tu32\t\t\tl_threshold;\t/ lower threshold /\n+\tu32\t\t\tu_threshold;\t/ upper threshold /\n+\n+\tunsigned long\t\tcflags;\t\t/ config flags /\n+\n+\t/ 44/64 /\n+\tatomic_t\t\tconn_flags;\t/ flags to copy to conn /\n+\n \t__u16\t\t\ttun_type;\t/ tunnel type /\n \t__be16\t\t\ttun_port;\t/ tunnel port /\n \t__u16\t\t\ttun_flags;\t/ tunnel flags /\n \n-\trefcount_t\t\trefcnt;\t\t/ reference counter /\n-\tstruct ip_vs_stats stats; / statistics /\n-\tunsigned long\t\tidle_start;\t/ start time, jiffies /\n+\tu16\t\t\taf;\t\t/ address family /\n+\t__be16\t\t\tport;\t\t/ port number of the server /\n+\t/ 60/80 /\n+\tunion nf_inet_addr\taddr;\t\t/ IP address of the server /\n \n-\t/ connection counters and thresholds /\n-\tatomic_t\t\tactiveconns;\t/ active connections /\n+\t/ connection counters /\n \tatomic_t\t\ttotalconns;\t/ total connections /\n+\tatomic_t\t\tactiveconns;\t/ active connections /\n \tatomic_t\t\tpersistconns;\t/ persistent connections /\n-\t__u32\t\t\tu_threshold;\t/ upper threshold /\n-\t__u32\t\t\tl_threshold;\t/ lower threshold /\n-\t__u32\t\t\tl_threshold_val;/ used lower threshold /\n+\n+\trefcount_t\t\trefcnt;\t\t/ reference counter /\n+\tstruct ip_vs_stats stats; / statistics /\n+\tunsigned long\t\tidle_start;\t/ start time, jiffies /\n \n \t/ for destination cache /\n \tspinlock_t\t\tdst_lock;\t/ lock of dst_cache /\n@@ -1915,7 +1923,13 @@ static inline void ip_vs_dest_put_and_free(struct ip_vs_dest dest)\n \t\tkfree(dest);\n }\n \n-void ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode);\n+void ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload);\n+\n+/* Check if dest is in overloaded state /\n+static inline bool ip_vs_dest_is_overloaded(const struct ip_vs_dest dest)\n+{\n+\treturn READ_ONCE(dest-\u003el_threshold_val);\n+}\n \n /* IPVS sync daemon data and function prototypes\n * (from ip_vs_sync.c)\ndiff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c\nindex 6fa3e1dc534c3..5348c2f49b64e 100644\n--- a/net/netfilter/ipvs/ip_vs_conn.c\n+++ b/net/netfilter/ipvs/ip_vs_conn.c\n@@ -1150,8 +1150,8 @@ ip_vs_bind_dest(struct ip_vs_conn cp, struct ip_vs_dest dest)\n \t\tif (!(flags \u0026 IP_VS_CONN_F_INACTIVE))\n \t\t\tatomic_inc(\u0026dest-\u003eactiveconns);\n \t\ttc = atomic_inc_return(\u0026dest-\u003etotalconns);\n-\t\tif (tc == READ_ONCE(dest-\u003eu_threshold))\n-\t\t\tip_vs_dest_update_overload(dest, 1);\n+\t\tif (tc \u003e= READ_ONCE(dest-\u003eu_threshold_val))\n+\t\t\tip_vs_dest_update_overload(dest, true);\n \t} else {\n \t\t/* It is a persistent connection/template, so increase\n \t\t the persistent connection counter /\n@@ -1243,8 +1243,8 @@ static inline void ip_vs_unbind_dest(struct ip_vs_conn cp)\n \t\tif (!(cp-\u003eflags \u0026 IP_VS_CONN_F_INACTIVE))\n \t\t\tatomic_dec(\u0026dest-\u003eactiveconns);\n \t\ttc = atomic_fetch_dec(\u0026dest-\u003etotalconns);\n-\t\tif (tc == READ_ONCE(dest-\u003el_threshold_val))\n-\t\t\tip_vs_dest_update_overload(dest, -1);\n+\t\tif (tc \u003c= READ_ONCE(dest-\u003el_threshold_val))\n+\t\t\tip_vs_dest_update_overload(dest, false);\n \t} else {\n \t\t/* It is a persistent connection/template, so decrease\n \t\t the persistent connection counter /\ndiff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c\nindex 4c1c739446b76..3003547dcabe5 100644\n--- a/net/netfilter/ipvs/ip_vs_ctl.c\n+++ b/net/netfilter/ipvs/ip_vs_ctl.c\n@@ -1309,32 +1309,32 @@ void ip_vs_stats_free(struct ip_vs_stats stats)\n * - conns reach u_threshold and exceed it: set the flag\n * - conns go below l_threshold (or 75% of u_threshold): clear the flag\n /\n-static void __ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode)\n+static void __ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload)\n {\n \tint conns;\n \tu32 l, u;\n \n \tlockdep_assert_held(\u0026dest-\u003edst_lock);\n \tu = READ_ONCE(dest-\u003eu_threshold);\n-\tif (!u)\n-\t\tgoto unset;\n-\tl = READ_ONCE(dest-\u003el_threshold_val);\n-\tconns = atomic_read(\u0026dest-\u003etotalconns);\n-\tif (conns \u003e= (mode \u003e 0 ? l : u)) {\n-\t\tdest-\u003eflags \|= IP_VS_DEST_F_OVERLOAD;\n-\t\treturn;\n+\tif (u) {\n+\t\t/ Low threshold defaults to 75% of upper threshold /\n+\t\tl = READ_ONCE(dest-\u003el_threshold) ? : (u - (u \u003e\u003e 2));\n+\t\tconns = atomic_read(\u0026dest-\u003etotalconns);\n+\t\tif (conns \u003e= (overload ? l : u)) {\n+\t\t\tWRITE_ONCE(dest-\u003eu_threshold_val, INT_MAX);\n+\t\t\tWRITE_ONCE(dest-\u003el_threshold_val, l);\n+\t\t\treturn;\n+\t\t}\n \t}\n-\tif (conns \u003e= (mode \u003c 0 ? u : l))\n-\t\treturn;\n \n-unset:\n-\tdest-\u003eflags \u0026= ~IP_VS_DEST_F_OVERLOAD;\n+\tWRITE_ONCE(dest-\u003eu_threshold_val, u ? : INT_MAX);\n+\tWRITE_ONCE(dest-\u003el_threshold_val, 0);\n }\n \n-void ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode)\n+void ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload)\n {\n \tspin_lock_bh(\u0026dest-\u003edst_lock);\n-\t__ip_vs_dest_update_overload(dest, mode);\n+\t__ip_vs_dest_update_overload(dest, overload);\n \tspin_unlock_bh(\u0026dest-\u003edst_lock);\n }\n \n@@ -1406,15 +1406,13 @@ __ip_vs_update_dest(struct ip_vs_service svc, struct ip_vs_dest dest,\n \n \tif (READ_ONCE(dest-\u003eu_threshold) != udest-\u003eu_threshold \|\|\n \t READ_ONCE(dest-\u003el_threshold) != udest-\u003el_threshold) {\n+\t\tbool overload;\n+\n \t\tspin_lock_bh(\u0026dest-\u003edst_lock);\n \t\tWRITE_ONCE(dest-\u003eu_threshold, udest-\u003eu_threshold);\n \t\tWRITE_ONCE(dest-\u003el_threshold, udest-\u003el_threshold);\n-\t\t/ Low threshold defaults to 75% of upper threshold /\n-\t\tWRITE_ONCE(dest-\u003el_threshold_val,\n-\t\t\t udest-\u003el_threshold ? :\n-\t\t\t (udest-\u003eu_threshold -\n-\t\t\t (udest-\u003eu_threshold \u003e\u003e 2)));\n-\t\t__ip_vs_dest_update_overload(dest, 0);\n+\t\toverload = ip_vs_dest_is_overloaded(dest);\n+\t\t__ip_vs_dest_update_overload(dest, overload);\n \t\tspin_unlock_bh(\u0026dest-\u003edst_lock);\n \t}\n \ndiff --git a/net/netfilter/ipvs/ip_vs_dh.c b/net/netfilter/ipvs/ip_vs_dh.c\nindex 43abed7a26a6a..95e52950adbb7 100644\n--- a/net/netfilter/ipvs/ip_vs_dh.c\n+++ b/net/netfilter/ipvs/ip_vs_dh.c\n@@ -195,16 +195,6 @@ static int ip_vs_dh_dest_changed(struct ip_vs_service svc,\n }\n \n \n-/\n- If the dest flags is set with IP_VS_DEST_F_OVERLOAD,\n- * consider that the server is overloaded here.\n- /\n-static inline int is_overloaded(struct ip_vs_dest dest)\n-{\n-\treturn dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD;\n-}\n-\n-\n /\n Destination hashing scheduling\n /\n@@ -219,10 +209,8 @@ ip_vs_dh_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \n \ts = (struct ip_vs_dh_state ) svc-\u003esched_data;\n \tdest = ip_vs_dh_get(svc-\u003eaf, s, \u0026iph-\u003edaddr);\n-\tif (!dest \|\|\n-\t !(dest-\u003ecflags \u0026 IP_VS_DEST_CF_AVAILABLE)\n-\t \|\| atomic_read(\u0026dest-\u003eweight) \u003c= 0\n-\t \|\| is_overloaded(dest)) {\n+\tif (!dest \|\| atomic_read(\u0026dest-\u003eweight) \u003c= 0 \|\|\n+\t ip_vs_dest_is_overloaded(dest)) {\n \t\tip_vs_scheduler_err(svc, \"no destination available\");\n \t\treturn NULL;\n \t}\ndiff --git a/net/netfilter/ipvs/ip_vs_fo.c b/net/netfilter/ipvs/ip_vs_fo.c\nindex d657b47c6511f..e07fa33f6d527 100644\n--- a/net/netfilter/ipvs/ip_vs_fo.c\n+++ b/net/netfilter/ipvs/ip_vs_fo.c\n@@ -29,7 +29,7 @@ ip_vs_fo_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t * Find virtual server with highest weight and send it traffic\n \t /\n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (!(dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD) \u0026\u0026\n+\t\tif (!ip_vs_dest_is_overloaded(dest) \u0026\u0026\n \t\t atomic_read(\u0026dest-\u003eweight) \u003e hw) {\n \t\t\thweight = dest;\n \t\t\thw = atomic_read(\u0026dest-\u003eweight);\ndiff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c\nindex 693bcc82ccb77..bff109c1c959b 100644\n--- a/net/netfilter/ipvs/ip_vs_lblc.c\n+++ b/net/netfilter/ipvs/ip_vs_lblc.c\n@@ -414,7 +414,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service svc)\n \t * new connection.\n \t /\n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(dest))\n \t\t\tcontinue;\n \t\tif (atomic_read(\u0026dest-\u003eweight) \u003e 0) {\n \t\t\tleast = dest;\n@@ -429,7 +429,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service svc)\n \t /\n nextstage:\n \tlist_for_each_entry_continue_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(dest))\n \t\t\tcontinue;\n \n \t\tdoh = ip_vs_dest_conn_overhead(dest);\ndiff --git a/net/netfilter/ipvs/ip_vs_lblcr.c b/net/netfilter/ipvs/ip_vs_lblcr.c\nindex f53f05ceea36f..c2853e07e7872 100644\n--- a/net/netfilter/ipvs/ip_vs_lblcr.c\n+++ b/net/netfilter/ipvs/ip_vs_lblcr.c\n@@ -166,7 +166,7 @@ static inline struct ip_vs_dest ip_vs_dest_set_min(struct ip_vs_dest_set set)\n \t/ select the first destination server, whose weight \u003e 0 /\n \tlist_for_each_entry_rcu(e, \u0026set-\u003elist, list) {\n \t\tleast = e-\u003edest;\n-\t\tif (least-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(least))\n \t\t\tcontinue;\n \n \t\tif ((atomic_read(\u0026least-\u003eweight) \u003e 0) \u0026\u0026\n@@ -181,7 +181,7 @@ static inline struct ip_vs_dest ip_vs_dest_set_min(struct ip_vs_dest_set set)\n nextstage:\n \tlist_for_each_entry_continue_rcu(e, \u0026set-\u003elist, list) {\n \t\tdest = e-\u003edest;\n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(dest))\n \t\t\tcontinue;\n \n \t\tdoh = ip_vs_dest_conn_overhead(dest);\n@@ -577,7 +577,7 @@ __ip_vs_lblcr_schedule(struct ip_vs_service svc)\n \t * new connection.\n \t /\n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(dest))\n \t\t\tcontinue;\n \n \t\tif (atomic_read(\u0026dest-\u003eweight) \u003e 0) {\n@@ -593,7 +593,7 @@ __ip_vs_lblcr_schedule(struct ip_vs_service svc)\n \t /\n nextstage:\n \tlist_for_each_entry_continue_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(dest))\n \t\t\tcontinue;\n \n \t\tdoh = ip_vs_dest_conn_overhead(dest);\ndiff --git a/net/netfilter/ipvs/ip_vs_lc.c b/net/netfilter/ipvs/ip_vs_lc.c\nindex 18b976a7c4d20..9002f491bff68 100644\n--- a/net/netfilter/ipvs/ip_vs_lc.c\n+++ b/net/netfilter/ipvs/ip_vs_lc.c\n@@ -38,7 +38,7 @@ ip_vs_lc_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t /\n \n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif ((dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD) \|\|\n+\t\tif (ip_vs_dest_is_overloaded(dest) \|\|\n \t\t atomic_read(\u0026dest-\u003eweight) == 0)\n \t\t\tcontinue;\n \t\tdoh = ip_vs_dest_conn_overhead(dest);\ndiff --git a/net/netfilter/ipvs/ip_vs_mh.c b/net/netfilter/ipvs/ip_vs_mh.c\nindex 020863047562d..d70b23aec5fec 100644\n--- a/net/netfilter/ipvs/ip_vs_mh.c\n+++ b/net/netfilter/ipvs/ip_vs_mh.c\n@@ -80,7 +80,7 @@ static inline void generate_hash_secret(hsiphash_key_t hash1,\n static inline bool is_unavailable(struct ip_vs_dest dest)\n {\n \treturn atomic_read(\u0026dest-\u003eweight) \u003c= 0 \|\|\n-\t dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD;\n+\t ip_vs_dest_is_overloaded(dest);\n }\n \n /* Returns hash value for IPVS MH entry /\ndiff --git a/net/netfilter/ipvs/ip_vs_nq.c b/net/netfilter/ipvs/ip_vs_nq.c\nindex ada158c610ce1..7cc28902086e7 100644\n--- a/net/netfilter/ipvs/ip_vs_nq.c\n+++ b/net/netfilter/ipvs/ip_vs_nq.c\n@@ -72,7 +72,7 @@ ip_vs_nq_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n \n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD \|\|\n+\t\tif (ip_vs_dest_is_overloaded(dest) \|\|\n \t\t !atomic_read(\u0026dest-\u003eweight))\n \t\t\tcontinue;\n \ndiff --git a/net/netfilter/ipvs/ip_vs_ovf.c b/net/netfilter/ipvs/ip_vs_ovf.c\nindex c5c67df80a0b3..eaa3a7ae6efa6 100644\n--- a/net/netfilter/ipvs/ip_vs_ovf.c\n+++ b/net/netfilter/ipvs/ip_vs_ovf.c\n@@ -33,7 +33,7 @@ ip_vs_ovf_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t/\n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n \t\tw = atomic_read(\u0026dest-\u003eweight);\n-\t\tif ((dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD) \|\|\n+\t\tif (ip_vs_dest_is_overloaded(dest) \|\|\n \t\t atomic_read(\u0026dest-\u003eactiveconns) \u003e w \|\|\n \t\t w == 0)\n \t\t\tcontinue;\ndiff --git a/net/netfilter/ipvs/ip_vs_rr.c b/net/netfilter/ipvs/ip_vs_rr.c\nindex 4125ee561cdc3..bd17cdd092f5f 100644\n--- a/net/netfilter/ipvs/ip_vs_rr.c\n+++ b/net/netfilter/ipvs/ip_vs_rr.c\n@@ -66,7 +66,7 @@ ip_vs_rr_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t\tlist_for_each_entry_continue_rcu(dest,\n \t\t\t\t\t\t \u0026svc-\u003edestinations,\n \t\t\t\t\t\t n_list) {\n-\t\t\tif (!(dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD) \u0026\u0026\n+\t\t\tif (!ip_vs_dest_is_overloaded(dest) \u0026\u0026\n \t\t\t atomic_read(\u0026dest-\u003eweight) \u003e 0)\n \t\t\t\t/* HIT /\n \t\t\t\tgoto out;\ndiff --git a/net/netfilter/ipvs/ip_vs_sed.c b/net/netfilter/ipvs/ip_vs_sed.c\nindex 245a323c84cd3..7925f4d28fce9 100644\n--- a/net/netfilter/ipvs/ip_vs_sed.c\n+++ b/net/netfilter/ipvs/ip_vs_sed.c\n@@ -75,7 +75,7 @@ ip_vs_sed_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t /\n \n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (!(dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD) \u0026\u0026\n+\t\tif (!ip_vs_dest_is_overloaded(dest) \u0026\u0026\n \t\t atomic_read(\u0026dest-\u003eweight) \u003e 0) {\n \t\t\tleast = dest;\n \t\t\tloh = ip_vs_sed_dest_overhead(least);\n@@ -90,7 +90,7 @@ ip_vs_sed_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t /\n nextstage:\n \tlist_for_each_entry_continue_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(dest))\n \t\t\tcontinue;\n \t\tdoh = ip_vs_sed_dest_overhead(dest);\n \t\tif ((__s64)loh atomic_read(\u0026dest-\u003eweight) \u003e\ndiff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c\nindex cd67066e3b261..c24dd5cb7e478 100644\n--- a/net/netfilter/ipvs/ip_vs_sh.c\n+++ b/net/netfilter/ipvs/ip_vs_sh.c\n@@ -73,7 +73,7 @@ struct ip_vs_sh_state {\n static inline bool is_unavailable(struct ip_vs_dest dest)\n {\n \treturn atomic_read(\u0026dest-\u003eweight) \u003c= 0 \|\|\n-\t dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD;\n+\t ip_vs_dest_is_overloaded(dest);\n }\n \n /\ndiff --git a/net/netfilter/ipvs/ip_vs_twos.c b/net/netfilter/ipvs/ip_vs_twos.c\nindex dbb7f5fd4688a..86186122a1f01 100644\n--- a/net/netfilter/ipvs/ip_vs_twos.c\n+++ b/net/netfilter/ipvs/ip_vs_twos.c\n@@ -52,7 +52,7 @@ static struct ip_vs_dest ip_vs_twos_schedule(struct ip_vs_service svc,\n \n \t/* Generate a random weight between [0,sum of all weights) /\n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (!(dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)) {\n+\t\tif (!ip_vs_dest_is_overloaded(dest)) {\n \t\t\tweight = atomic_read(\u0026dest-\u003eweight);\n \t\t\tif (weight \u003e 0) {\n \t\t\t\ttotal_weight += weight;\n@@ -75,7 +75,7 @@ static struct ip_vs_dest ip_vs_twos_schedule(struct ip_vs_service svc,\n \n \t/ Pick two weighted servers /\n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(dest))\n \t\t\tcontinue;\n \n \t\tweight = atomic_read(\u0026dest-\u003eweight);\ndiff --git a/net/netfilter/ipvs/ip_vs_wlc.c b/net/netfilter/ipvs/ip_vs_wlc.c\nindex 9da445ca09a14..08e9e22f72bf8 100644\n--- a/net/netfilter/ipvs/ip_vs_wlc.c\n+++ b/net/netfilter/ipvs/ip_vs_wlc.c\n@@ -47,7 +47,7 @@ ip_vs_wlc_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t /\n \n \tlist_for_each_entry_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (!(dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD) \u0026\u0026\n+\t\tif (!ip_vs_dest_is_overloaded(dest) \u0026\u0026\n \t\t atomic_read(\u0026dest-\u003eweight) \u003e 0) {\n \t\t\tleast = dest;\n \t\t\tloh = ip_vs_dest_conn_overhead(least);\n@@ -62,7 +62,7 @@ ip_vs_wlc_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t /\n nextstage:\n \tlist_for_each_entry_continue_rcu(dest, \u0026svc-\u003edestinations, n_list) {\n-\t\tif (dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD)\n+\t\tif (ip_vs_dest_is_overloaded(dest))\n \t\t\tcontinue;\n \t\tdoh = ip_vs_dest_conn_overhead(dest);\n \t\tif ((__s64)loh atomic_read(\u0026dest-\u003eweight) \u003e\ndiff --git a/net/netfilter/ipvs/ip_vs_wrr.c b/net/netfilter/ipvs/ip_vs_wrr.c\nindex 2dcff1040da52..fad69bae5a22b 100644\n--- a/net/netfilter/ipvs/ip_vs_wrr.c\n+++ b/net/netfilter/ipvs/ip_vs_wrr.c\n@@ -176,7 +176,7 @@ ip_vs_wrr_schedule(struct ip_vs_service svc, const struct sk_buff skb,\n \t\tlist_for_each_entry_continue_rcu(dest,\n \t\t\t\t\t\t \u0026svc-\u003edestinations,\n \t\t\t\t\t\t n_list) {\n-\t\t\tif (!(dest-\u003eflags \u0026 IP_VS_DEST_F_OVERLOAD) \u0026\u0026\n+\t\t\tif (!ip_vs_dest_is_overloaded(dest) \u0026\u0026\n \t\t\t atomic_read(\u0026dest-\u003eweight) \u003e= mark-\u003ecw)\n \t\t\t\tgoto found;\n \t\t\tif (dest == stop)\n" }
2/1	2026/09/07 22:10	agent	patch-evaluator	1m Model: core Args: null Results: { "EnableConfigs": [ "IP_VS", "NETFILTER", "INET" ], "FocusSymbols": [ "ip_vs_dest_update_overload", "ip_vs_bind_dest", "ip_vs_unbind_dest", "__ip_vs_update_dest", "ip_vs_edit_dest", "ip_vs_add_dest", "ip_vs_rr_schedule", "ip_vs_wrr_schedule", "ip_vs_wlc_schedule", "ip_vs_lc_schedule", "ip_vs_fo_schedule", "ip_vs_ovf_schedule", "ip_vs_twos_schedule" ], "Reasoning": "The patch modifies the destination overload tracking logic and destination structure layout in the IPVS (IP Virtual Server) subsystem. It updates connection binding and unbinding thresholds, control plane destination updates, and scheduler overload evaluation across IPVS algorithms. These are reachable, executable network paths that should be fuzzed for race conditions, arithmetic or state handling bugs, and threshold edge cases.", "WorthFuzzing": true } Instruction: You are an expert Linux kernel maintainer and security engineer. Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller. IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in your workspace. Do NOT rely on internal assumptions. You must actively use your code access tools to inspect the actual source code, callers, and surrounding context. ================================================================================ 1. CORE TRIAGE PHILOSOPHY ================================================================================ The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs, and newly triggered assertions introduced by the patch series. - REACHABILITY IS THE PRIMARY GATE: Fuzzing can only discover bugs in code that can actually execute in standard virtualized environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap). If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed, regardless of whether it adds assertions or complex logic. - DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS: Patch authors routinely label changes as "cleanups", "refactorings", or state "No functional change intended". Do NOT take these claims at face value. Code refactorings that rearrange logic, introduce helper functions, or alter state management in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs. If reachable executable code is modified or refactored, it MUST be fuzzed. - NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED: When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON, VM_WARN_ON, BUG_ON, lockdep_assert) in reachable code paths, it enforces new or stricter invariants. Even if the author believes the invariant always holds, fuzzing is essential to verify whether an unusual sequence of operations can violate it. ================================================================================ 2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA) ================================================================================ Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories: - Non-kernel and non-executable changes: * Modifications to Documentation/, comments, or spelling fixes. * User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/) that do not affect the compiled kernel image (vmlinux) or kernel modules. * Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures. * Build system or Kconfig changes that do not alter compiled C logic. - Structurally unreachable hardware: * Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU. - Unreachable execution paths: * Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during physical PCI hot-unplug or manual sysfs driver unbinding. * Code paths exclusive to architectures other than the target architecture. ================================================================================ 3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA) ================================================================================ Return WorthFuzzing=true whenever the patch touches reachable executable code, including: - Core Subsystems: * Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/), BPF, scheduler, core networking, VFS, or syscall handling. - Refactorings and Code Cleanups: * Any restructuring of reachable data structures, helper abstractions, or algorithm flows. - Runtime Assertions and Defensive Checks: * Any introduction or alteration of assertions (WARN_ON, VM_WARN_ON, BUG_ON, etc.) in reachable paths. - Reachable Drivers and Protocols: Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.). ================================================================================ 4. EXTRACTING FocusSymbols (PREVENTING DILUTION) ================================================================================ When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer: - AVOID UBIQUITOUS LIFECYCLE HOT-PATHS: Do NOT list generic, ubiquitous functions called by almost every program in the corpus (including, but not limited to: general memory allocators and deallocators, page fault and trap handlers, or core synchronization primitives; this is not an exhaustive list). Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused", which severely dilutes fuzzing effort away from the actual changes. - TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS: List functions that specifically implement the logic being added or altered, or direct API entrypoints for the subsystem feature under review. - HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h): Compiler-inlined static functions (such as static inlines in mm/.h or include/linux/.h) lack distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters. If the changes are primarily in static inline helpers, identify non-static, feature-specific caller functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers). ================================================================================ 5. IDENTIFYING EnableConfigs ================================================================================ Identify any specific CONFIG_ options required to properly compile and reach the modified code: - Inspect Kconfig files and #ifdef guards; do not make assumptions. - Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed. - Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4"). Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit a029c18539e2bd4393bb8736df0003e422cb7c9b Author: syz-cluster <triage@syzkaller.com> Date: Mon Sep 7 22:10:16 2026 +0000 syz-cluster: applied patch under review diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h index 32fde731bceb7..9a83bff32569d 100644 --- a/include/net/ip_vs.h +++ b/include/net/ip_vs.h @@ -36,9 +36,6 @@ #define IP_VS_HDR_INVERSE 1 #define IP_VS_HDR_ICMP 2 -/* Destination Server Flags / -#define IP_VS_DEST_F_OVERLOAD 0x0002 / server is overloaded / - / Destination Server Config Flags / #define IP_VS_DEST_CF_AVAILABLE 0x0001 / server is available / @@ -973,32 +970,43 @@ struct ip_vs_dest_dst { and so on. / struct ip_vs_dest { + / Cacheline for hash table nodes - read-mostly / + struct list_head n_list; / for the dests in the service / struct hlist_node d_list; / for table with all the dests / - u16 af; / address family / - __be16 port; / port number of the server / - union nf_inet_addr addr; / IP address of the server / - volatile unsigned int flags; / dest status flags / - atomic_t conn_flags; / flags to copy to conn / atomic_t weight; / server weight / - unsigned long cflags; / config flags / atomic_t last_weight; / server latest weight / + + / connection thresholds / + u32 l_threshold_val;/ used lower threshold / + u32 u_threshold_val;/ used upper threshold / + / 32/48 / + u32 l_threshold; / lower threshold / + u32 u_threshold; / upper threshold / + + unsigned long cflags; / config flags / + + / 44/64 / + atomic_t conn_flags; / flags to copy to conn / + __u16 tun_type; / tunnel type / __be16 tun_port; / tunnel port / __u16 tun_flags; / tunnel flags / - refcount_t refcnt; / reference counter / - struct ip_vs_stats stats; / statistics / - unsigned long idle_start; / start time, jiffies / + u16 af; / address family / + __be16 port; / port number of the server / + / 60/80 / + union nf_inet_addr addr; / IP address of the server / - / connection counters and thresholds / - atomic_t activeconns; / active connections / + / connection counters / atomic_t totalconns; / total connections / + atomic_t activeconns; / active connections / atomic_t persistconns; / persistent connections / - __u32 u_threshold; / upper threshold / - __u32 l_threshold; / lower threshold / - __u32 l_threshold_val;/ used lower threshold / + + refcount_t refcnt; / reference counter / + struct ip_vs_stats stats; / statistics / + unsigned long idle_start; / start time, jiffies / / for destination cache / spinlock_t dst_lock; / lock of dst_cache / @@ -1915,7 +1923,13 @@ static inline void ip_vs_dest_put_and_free(struct ip_vs_dest dest) kfree(dest); } -void ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode); +void ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload); + +/* Check if dest is in overloaded state / +static inline bool ip_vs_dest_is_overloaded(const struct ip_vs_dest dest) +{ + return READ_ONCE(dest->l_threshold_val); +} /* IPVS sync daemon data and function prototypes * (from ip_vs_sync.c) diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c index 6fa3e1dc534c3..5348c2f49b64e 100644 --- a/net/netfilter/ipvs/ip_vs_conn.c +++ b/net/netfilter/ipvs/ip_vs_conn.c @@ -1150,8 +1150,8 @@ ip_vs_bind_dest(struct ip_vs_conn cp, struct ip_vs_dest dest) if (!(flags & IP_VS_CONN_F_INACTIVE)) atomic_inc(&dest->activeconns); tc = atomic_inc_return(&dest->totalconns); - if (tc == READ_ONCE(dest->u_threshold)) - ip_vs_dest_update_overload(dest, 1); + if (tc >= READ_ONCE(dest->u_threshold_val)) + ip_vs_dest_update_overload(dest, true); } else { /* It is a persistent connection/template, so increase the persistent connection counter / @@ -1243,8 +1243,8 @@ static inline void ip_vs_unbind_dest(struct ip_vs_conn cp) if (!(cp->flags & IP_VS_CONN_F_INACTIVE)) atomic_dec(&dest->activeconns); tc = atomic_fetch_dec(&dest->totalconns); - if (tc == READ_ONCE(dest->l_threshold_val)) - ip_vs_dest_update_overload(dest, -1); + if (tc <= READ_ONCE(dest->l_threshold_val)) + ip_vs_dest_update_overload(dest, false); } else { /* It is a persistent connection/template, so decrease the persistent connection counter / diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index 4c1c739446b76..3003547dcabe5 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -1309,32 +1309,32 @@ void ip_vs_stats_free(struct ip_vs_stats stats) * - conns reach u_threshold and exceed it: set the flag * - conns go below l_threshold (or 75% of u_threshold): clear the flag / -static void __ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode) +static void __ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload) { int conns; u32 l, u; lockdep_assert_held(&dest->dst_lock); u = READ_ONCE(dest->u_threshold); - if (!u) - goto unset; - l = READ_ONCE(dest->l_threshold_val); - conns = atomic_read(&dest->totalconns); - if (conns >= (mode > 0 ? l : u)) { - dest->flags \|= IP_VS_DEST_F_OVERLOAD; - return; + if (u) { + / Low threshold defaults to 75% of upper threshold / + l = READ_ONCE(dest->l_threshold) ? : (u - (u >> 2)); + conns = atomic_read(&dest->totalconns); + if (conns >= (overload ? l : u)) { + WRITE_ONCE(dest->u_threshold_val, INT_MAX); + WRITE_ONCE(dest->l_threshold_val, l); + return; + } } - if (conns >= (mode < 0 ? u : l)) - return; -unset: - dest->flags &= ~IP_VS_DEST_F_OVERLOAD; + WRITE_ONCE(dest->u_threshold_val, u ? : INT_MAX); + WRITE_ONCE(dest->l_threshold_val, 0); } -void ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode) +void ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload) { spin_lock_bh(&dest->dst_lock); - __ip_vs_dest_update_overload(dest, mode); + __ip_vs_dest_update_overload(dest, overload); spin_unlock_bh(&dest->dst_lock); } @@ -1406,15 +1406,13 @@ __ip_vs_update_dest(struct ip_vs_service svc, struct ip_vs_dest dest, if (READ_ONCE(dest->u_threshold) != udest->u_threshold \|\| READ_ONCE(dest->l_threshold) != udest->l_threshold) { + bool overload; + spin_lock_bh(&dest->dst_lock); WRITE_ONCE(dest->u_threshold, udest->u_threshold); WRITE_ONCE(dest->l_threshold, udest->l_threshold); - / Low threshold defaults to 75% of upper threshold / - WRITE_ONCE(dest->l_threshold_val, - udest->l_threshold ? : - (udest->u_threshold - - (udest->u_threshold >> 2))); - __ip_vs_dest_update_overload(dest, 0); + overload = ip_vs_dest_is_overloaded(dest); + __ip_vs_dest_update_overload(dest, overload); spin_unlock_bh(&dest->dst_lock); } diff --git a/net/netfilter/ipvs/ip_vs_dh.c b/net/netfilter/ipvs/ip_vs_dh.c index 43abed7a26a6a..95e52950adbb7 100644 --- a/net/netfilter/ipvs/ip_vs_dh.c +++ b/net/netfilter/ipvs/ip_vs_dh.c @@ -195,16 +195,6 @@ static int ip_vs_dh_dest_changed(struct ip_vs_service svc, } -/* - * If the dest flags is set with IP_VS_DEST_F_OVERLOAD, - * consider that the server is overloaded here. - / -static inline int is_overloaded(struct ip_vs_dest dest) -{ - return dest->flags & IP_VS_DEST_F_OVERLOAD; -} - - /* * Destination hashing scheduling / @@ -219,10 +209,8 @@ ip_vs_dh_schedule(struct ip_vs_service svc, const struct sk_buff skb, s = (struct ip_vs_dh_state ) svc->sched_data; dest = ip_vs_dh_get(svc->af, s, &iph->daddr); - if (!dest \|\| - !(dest->cflags & IP_VS_DEST_CF_AVAILABLE) - \|\| atomic_read(&dest->weight) <= 0 - \|\| is_overloaded(dest)) { + if (!dest \|\| atomic_read(&dest->weight) <= 0 \|\| + ip_vs_dest_is_overloaded(dest)) { ip_vs_scheduler_err(svc, "no destination available"); return NULL; } diff --git a/net/netfilter/ipvs/ip_vs_fo.c b/net/netfilter/ipvs/ip_vs_fo.c index d657b47c6511f..e07fa33f6d527 100644 --- a/net/netfilter/ipvs/ip_vs_fo.c +++ b/net/netfilter/ipvs/ip_vs_fo.c @@ -29,7 +29,7 @@ ip_vs_fo_schedule(struct ip_vs_service svc, const struct sk_buff skb, * Find virtual server with highest weight and send it traffic / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) > hw) { hweight = dest; hw = atomic_read(&dest->weight); diff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c index 693bcc82ccb77..bff109c1c959b 100644 --- a/net/netfilter/ipvs/ip_vs_lblc.c +++ b/net/netfilter/ipvs/ip_vs_lblc.c @@ -414,7 +414,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service svc) * new connection. / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; if (atomic_read(&dest->weight) > 0) { least = dest; @@ -429,7 +429,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service svc) / nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_dest_conn_overhead(dest); diff --git a/net/netfilter/ipvs/ip_vs_lblcr.c b/net/netfilter/ipvs/ip_vs_lblcr.c index f53f05ceea36f..c2853e07e7872 100644 --- a/net/netfilter/ipvs/ip_vs_lblcr.c +++ b/net/netfilter/ipvs/ip_vs_lblcr.c @@ -166,7 +166,7 @@ static inline struct ip_vs_dest ip_vs_dest_set_min(struct ip_vs_dest_set set) / select the first destination server, whose weight > 0 / list_for_each_entry_rcu(e, &set->list, list) { least = e->dest; - if (least->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(least)) continue; if ((atomic_read(&least->weight) > 0) && @@ -181,7 +181,7 @@ static inline struct ip_vs_dest ip_vs_dest_set_min(struct ip_vs_dest_set set) nextstage: list_for_each_entry_continue_rcu(e, &set->list, list) { dest = e->dest; - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_dest_conn_overhead(dest); @@ -577,7 +577,7 @@ __ip_vs_lblcr_schedule(struct ip_vs_service svc) * new connection. / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; if (atomic_read(&dest->weight) > 0) { @@ -593,7 +593,7 @@ __ip_vs_lblcr_schedule(struct ip_vs_service svc) / nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_dest_conn_overhead(dest); diff --git a/net/netfilter/ipvs/ip_vs_lc.c b/net/netfilter/ipvs/ip_vs_lc.c index 18b976a7c4d20..9002f491bff68 100644 --- a/net/netfilter/ipvs/ip_vs_lc.c +++ b/net/netfilter/ipvs/ip_vs_lc.c @@ -38,7 +38,7 @@ ip_vs_lc_schedule(struct ip_vs_service svc, const struct sk_buff skb, / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if ((dest->flags & IP_VS_DEST_F_OVERLOAD) \|\| + if (ip_vs_dest_is_overloaded(dest) \|\| atomic_read(&dest->weight) == 0) continue; doh = ip_vs_dest_conn_overhead(dest); diff --git a/net/netfilter/ipvs/ip_vs_mh.c b/net/netfilter/ipvs/ip_vs_mh.c index 020863047562d..d70b23aec5fec 100644 --- a/net/netfilter/ipvs/ip_vs_mh.c +++ b/net/netfilter/ipvs/ip_vs_mh.c @@ -80,7 +80,7 @@ static inline void generate_hash_secret(hsiphash_key_t hash1, static inline bool is_unavailable(struct ip_vs_dest dest) { return atomic_read(&dest->weight) <= 0 \|\| - dest->flags & IP_VS_DEST_F_OVERLOAD; + ip_vs_dest_is_overloaded(dest); } /* Returns hash value for IPVS MH entry / diff --git a/net/netfilter/ipvs/ip_vs_nq.c b/net/netfilter/ipvs/ip_vs_nq.c index ada158c610ce1..7cc28902086e7 100644 --- a/net/netfilter/ipvs/ip_vs_nq.c +++ b/net/netfilter/ipvs/ip_vs_nq.c @@ -72,7 +72,7 @@ ip_vs_nq_schedule(struct ip_vs_service svc, const struct sk_buff skb, list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD \|\| + if (ip_vs_dest_is_overloaded(dest) \|\| !atomic_read(&dest->weight)) continue; diff --git a/net/netfilter/ipvs/ip_vs_ovf.c b/net/netfilter/ipvs/ip_vs_ovf.c index c5c67df80a0b3..eaa3a7ae6efa6 100644 --- a/net/netfilter/ipvs/ip_vs_ovf.c +++ b/net/netfilter/ipvs/ip_vs_ovf.c @@ -33,7 +33,7 @@ ip_vs_ovf_schedule(struct ip_vs_service svc, const struct sk_buff skb, / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { w = atomic_read(&dest->weight); - if ((dest->flags & IP_VS_DEST_F_OVERLOAD) \|\| + if (ip_vs_dest_is_overloaded(dest) \|\| atomic_read(&dest->activeconns) > w \|\| w == 0) continue; diff --git a/net/netfilter/ipvs/ip_vs_rr.c b/net/netfilter/ipvs/ip_vs_rr.c index 4125ee561cdc3..bd17cdd092f5f 100644 --- a/net/netfilter/ipvs/ip_vs_rr.c +++ b/net/netfilter/ipvs/ip_vs_rr.c @@ -66,7 +66,7 @@ ip_vs_rr_schedule(struct ip_vs_service svc, const struct sk_buff skb, list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) > 0) /* HIT / goto out; diff --git a/net/netfilter/ipvs/ip_vs_sed.c b/net/netfilter/ipvs/ip_vs_sed.c index 245a323c84cd3..7925f4d28fce9 100644 --- a/net/netfilter/ipvs/ip_vs_sed.c +++ b/net/netfilter/ipvs/ip_vs_sed.c @@ -75,7 +75,7 @@ ip_vs_sed_schedule(struct ip_vs_service svc, const struct sk_buff skb, / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) > 0) { least = dest; loh = ip_vs_sed_dest_overhead(least); @@ -90,7 +90,7 @@ ip_vs_sed_schedule(struct ip_vs_service svc, const struct sk_buff skb, / nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_sed_dest_overhead(dest); if ((__s64)loh atomic_read(&dest->weight) > diff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c index cd67066e3b261..c24dd5cb7e478 100644 --- a/net/netfilter/ipvs/ip_vs_sh.c +++ b/net/netfilter/ipvs/ip_vs_sh.c @@ -73,7 +73,7 @@ struct ip_vs_sh_state { static inline bool is_unavailable(struct ip_vs_dest dest) { return atomic_read(&dest->weight) <= 0 \|\| - dest->flags & IP_VS_DEST_F_OVERLOAD; + ip_vs_dest_is_overloaded(dest); } / diff --git a/net/netfilter/ipvs/ip_vs_twos.c b/net/netfilter/ipvs/ip_vs_twos.c index dbb7f5fd4688a..86186122a1f01 100644 --- a/net/netfilter/ipvs/ip_vs_twos.c +++ b/net/netfilter/ipvs/ip_vs_twos.c @@ -52,7 +52,7 @@ static struct ip_vs_dest ip_vs_twos_schedule(struct ip_vs_service svc, /* Generate a random weight between [0,sum of all weights) / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD)) { + if (!ip_vs_dest_is_overloaded(dest)) { weight = atomic_read(&dest->weight); if (weight > 0) { total_weight += weight; @@ -75,7 +75,7 @@ static struct ip_vs_dest ip_vs_twos_schedule(struct ip_vs_service svc, / Pick two weighted servers / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; weight = atomic_read(&dest->weight); diff --git a/net/netfilter/ipvs/ip_vs_wlc.c b/net/netfilter/ipvs/ip_vs_wlc.c index 9da445ca09a14..08e9e22f72bf8 100644 --- a/net/netfilter/ipvs/ip_vs_wlc.c +++ b/net/netfilter/ipvs/ip_vs_wlc.c @@ -47,7 +47,7 @@ ip_vs_wlc_schedule(struct ip_vs_service svc, const struct sk_buff skb, / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) > 0) { least = dest; loh = ip_vs_dest_conn_overhead(least); @@ -62,7 +62,7 @@ ip_vs_wlc_schedule(struct ip_vs_service svc, const struct sk_buff skb, / nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_dest_conn_overhead(dest); if ((__s64)loh atomic_read(&dest->weight) > diff --git a/net/netfilter/ipvs/ip_vs_wrr.c b/net/netfilter/ipvs/ip_vs_wrr.c index 2dcff1040da52..fad69bae5a22b 100644 --- a/net/netfilter/ipvs/ip_vs_wrr.c +++ b/net/netfilter/ipvs/ip_vs_wrr.c @@ -176,7 +176,7 @@ ip_vs_wrr_schedule(struct ip_vs_service svc, const struct sk_buff skb, list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) >= mark->cw) goto found; if (dest == stop)
3/2	2026/09/07 22:10	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 10140 output: 32 thoughts: 834 Thoughts: Analyzing the IPVS Overload Patch Okay, let's dive into this patch for the IPVS subsystem. My initial thought is to methodically break this down. First, I want to get a good handle on the scope of the changes. The patch targets several areas. The most significant changes seem to be in `include/net/ip_vs.h`. It's removing `IP_VS_DEST_F_OVERLOAD`, which is immediately interesting. This suggests a shift in how overload status is managed. The reorganization of `struct ip_vs_dest` to include `u_threshold_val` and focus on cacheline alignment is another point to consider. I'll need to check how that impacts existing data structures and potential lock contention. Also, a new inline helper function `ip_vs_dest_is_overloaded()` is defined. The changes in `ip_vs_conn.c` are crucial. The conditionals in `ip_vs_bind_dest` and `ip_vs_unbind_dest` that now compare the traffic count to `u_threshold_val` are a critical shift. Essentially it changes the overloard calculation. The use of `READ_ONCE` here is good to see as it suggests memory barriers are being considered. I'll need to understand how `u_threshold_val` is populated and how the `ip_vs_dest_update_overload` function is being used to affect this threshold. The updates to `ip_vs_ctl.c` with the altered implementations of `__ip_vs_dest_update_overload` and `ip_vs_dest_update_overload` require close inspection. I'll need to see precisely how this impacts the control path and any potential race conditions. Finally, the fact that a whole slew of scheduler modules – `dh`, `fo`, `lblc`, `lblcr`, `lc`, `mh`, `nq`, `ovf`, `rr`, `sed`, `sh`, `twos`, `wlc`, and `wrr` – are being touched indicates a pervasive change in overload handling across various scheduling algorithms. This is significant. It's likely that the overload state directly impacts scheduling decisions, and therefore the effect of overload status on all the scheduling algorithms needs to be carefully evaluated, Before I get too deep into the code, I should probably check the Kconfig for IPVS to establish the exact configuration symbols in play, as this will help me establish the context for this patch. I expect this will also give me a better understanding of the rationale behind these changes.
4/2	2026/09/07 22:10	tool	grepper	0m Args: { "Expression": "config IP_VS", "PathPrefix": "net/netfilter/ipvs/" } Results: { "Output": "net/netfilter/ipvs/Kconfig-4-#\nnet/netfilter/ipvs/Kconfig:5:menuconfig IP_VS\nnet/netfilter/ipvs/Kconfig-6-\ttristate \"IP virtual server support\"\n--\nnet/netfilter/ipvs/Kconfig=286=comment 'IPVS SH scheduler'\nnet/netfilter/ipvs/Kconfig-287-\nnet/netfilter/ipvs/Kconfig:288:config IP_VS_SH_TAB_BITS\nnet/netfilter/ipvs/Kconfig-289-\tint \"IPVS source hashing table size (the Nth power of 2)\"\n--\nnet/netfilter/ipvs/Kconfig=301=comment 'IPVS MH scheduler'\nnet/netfilter/ipvs/Kconfig-302-\nnet/netfilter/ipvs/Kconfig:303:config IP_VS_MH_TAB_INDEX\nnet/netfilter/ipvs/Kconfig-304-\tint \"IPVS maglev hashing table index of size (the prime numbers)\"\n" }
5/2	2026/09/07 22:10	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 11826 output: 36 thoughts: 28 Thoughts: Here's my take on those thoughts, tailored for an expert audience: Diving into the IPVS Configuration Landscape Okay, so I need a refresher on the kernel configurations related to IPVS and the available scheduling algorithms. I'll head straight for the source – `net/netfilter/ipvs/Kconfig`. This is where the core decisions are made, right? I'm hoping to quickly identify the relevant symbols, dependencies, and any new additions since the last time I dug into this. I'm especially interested in whether any subtle changes have been made to the scheduler options, maybe new algorithms or dependencies I've missed. This Kconfig file will be the key to understanding the current feature set and build options available for configuring IPVS in a running system, or a build.
6/2	2026/09/07 22:10	tool	read-file	0m Args: { "File": "net/netfilter/ipvs/Kconfig", "FirstLine": 1, "LineCount": 80 } Results: { "Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\t#\n 3:\t# IP Virtual Server configuration\n 4:\t#\n 5:\tmenuconfig IP_VS\n 6:\t\ttristate \"IP virtual server support\"\n 7:\t\tdepends on INET \u0026\u0026 NETFILTER\n 8:\t\tdepends on (NF_CONNTRACK \|\| NF_CONNTRACK=n)\n 9:\t\thelp\n 10:\t\t IP Virtual Server support will let you build a high-performance\n 11:\t\t virtual server based on cluster of two or more real servers. This\n 12:\t\t option must be enabled for at least one of the clustered computers\n 13:\t\t that will take care of intercepting incoming connections to a\n 14:\t\t single IP address and scheduling them to real servers.\n 15:\t\n 16:\t\t Three request dispatching techniques are implemented, they are\n 17:\t\t virtual server via NAT, virtual server via tunneling and virtual\n 18:\t\t server via direct routing. The several scheduling algorithms can\n 19:\t\t be used to choose which server the connection is directed to,\n 20:\t\t thus load balancing can be achieved among the servers. For more\n 21:\t\t information and its administration program, please visit the\n 22:\t\t following URL: \u003chttp://www.linuxvirtualserver.org/\u003e.\n 23:\t\n 24:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 25:\t\t module, choose M here. If unsure, say N.\n 26:\t\n 27:\tif IP_VS\n 28:\t\n 29:\tconfig\tIP_VS_IPV6\n 30:\t\tbool \"IPv6 support for IPVS\"\n 31:\t\tdepends on IPV6 = y \|\| IP_VS = IPV6\n 32:\t\tselect NF_DEFRAG_IPV6\n 33:\t\thelp\n 34:\t\t Add IPv6 support to IPVS.\n 35:\t\n 36:\t\t Say Y if unsure.\n 37:\t\n 38:\tconfig\tIP_VS_DEBUG\n 39:\t\tbool \"IP virtual server debugging\"\n 40:\t\thelp\n 41:\t\t Say Y here if you want to get additional messages useful in\n 42:\t\t debugging the IP virtual server code. You can change the debug\n 43:\t\t level in /proc/sys/net/ipv4/vs/debug_level\n 44:\t\n 45:\tconfig\tIP_VS_TAB_BITS\n 46:\t\tint \"IPVS connection table size (the Nth power of 2)\"\n 47:\t\trange 8 20 if !64BIT\n 48:\t\trange 8 27 if 64BIT\n 49:\t\tdefault 12\n 50:\t\thelp\n 51:\t\t The IPVS connection hash table uses the chaining scheme to handle\n 52:\t\t hash collisions. Using a big IPVS connection hash table will greatly\n 53:\t\t reduce conflicts when there are hundreds of thousands of connections\n 54:\t\t in the hash table.\n 55:\t\n 56:\t\t Note the table size must be power of 2. The table size will be the\n 57:\t\t value of 2 to the your input number power. The number to choose is\n 58:\t\t from 8 to 27 for 64BIT(20 otherwise), the default number is 12,\n 59:\t\t which means the table size is 4096. Don't input the number too\n 60:\t\t small, otherwise you will lose performance on it. You can adapt the\n 61:\t\t table size yourself, according to your virtual server application.\n 62:\t\t It is good to set the table size not far less than the number of\n 63:\t\t connections per second multiplying average lasting time of\n 64:\t\t connection in the table. For example, your virtual server gets 200\n 65:\t\t connections per second, the connection lasts for 200 seconds in\n 66:\t\t average in the connection table, the table size should be not far\n 67:\t\t less than 200x200, it is good to set the table size 32768 (2**15).\n 68:\t\n 69:\t\t Another note that each connection occupies 128 bytes effectively and\n 70:\t\t each hash entry uses 8 bytes, so you can estimate how much memory is\n 71:\t\t needed for your box.\n 72:\t\n 73:\t\t You can overwrite this number setting conn_tab_bits module parameter\n 74:\t\t or by appending ip_vs.conn_tab_bits=? to the kernel command line if\n 75:\t\t IP VS was compiled built-in.\n 76:\t\n 77:\tcomment \"IPVS transport protocol load balancing support\"\n 78:\t\n 79:\tconfig\tIP_VS_PROTO_TCP\n 80:\t\tbool \"TCP load balancing support\"\n" }
7/2	2026/09/07 22:10	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 13313 output: 38 thoughts: 23 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Examining the IPVS Scheduler Configurations Alright, let's dive back into the `net/netfilter/ipvs/Kconfig` file. I'm specifically interested in getting a clearer picture of the scheduler configurations. I know the basics, but I need to refresh my memory and make sure I haven't missed anything crucial regarding the available scheduling algorithms and their associated options within the IPVS framework. I want to ensure I have a complete understanding of the configuration options, dependencies, and any potential caveats associated with specific scheduler selections. Time to see what's what.
8/2	2026/09/07 22:10	tool	read-file	0m Args: { "File": "net/netfilter/ipvs/Kconfig", "FirstLine": 81, "LineCount": 100 } Results: { "Contents": " 81:\t\thelp\n 82:\t\t This option enables support for load balancing TCP transport\n 83:\t\t protocol. Say Y if unsure.\n 84:\t\n 85:\tconfig\tIP_VS_PROTO_UDP\n 86:\t\tbool \"UDP load balancing support\"\n 87:\t\thelp\n 88:\t\t This option enables support for load balancing UDP transport\n 89:\t\t protocol. Say Y if unsure.\n 90:\t\n 91:\tconfig\tIP_VS_PROTO_AH_ESP\n 92:\t\tdef_bool IP_VS_PROTO_ESP \|\| IP_VS_PROTO_AH\n 93:\t\n 94:\tconfig\tIP_VS_PROTO_ESP\n 95:\t\tbool \"ESP load balancing support\"\n 96:\t\thelp\n 97:\t\t This option enables support for load balancing ESP (Encapsulation\n 98:\t\t Security Payload) transport protocol. Say Y if unsure.\n 99:\t\n 100:\tconfig\tIP_VS_PROTO_AH\n 101:\t\tbool \"AH load balancing support\"\n 102:\t\thelp\n 103:\t\t This option enables support for load balancing AH (Authentication\n 104:\t\t Header) transport protocol. Say Y if unsure.\n 105:\t\n 106:\tconfig IP_VS_PROTO_SCTP\n 107:\t\tbool \"SCTP load balancing support\"\n 108:\t\tselect NET_CRC32C\n 109:\t\thelp\n 110:\t\t This option enables support for load balancing SCTP transport\n 111:\t\t protocol. Say Y if unsure.\n 112:\t\n 113:\tcomment \"IPVS scheduler\"\n 114:\t\n 115:\tconfig\tIP_VS_RR\n 116:\t\ttristate \"round-robin scheduling\"\n 117:\t\thelp\n 118:\t\t The robin-robin scheduling algorithm simply directs network\n 119:\t\t connections to different real servers in a round-robin manner.\n 120:\t\n 121:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 122:\t\t module, choose M here. If unsure, say N.\n 123:\t \n 124:\tconfig\tIP_VS_WRR\n 125:\t\ttristate \"weighted round-robin scheduling\"\n 126:\t\thelp\n 127:\t\t The weighted robin-robin scheduling algorithm directs network\n 128:\t\t connections to different real servers based on server weights\n 129:\t\t in a round-robin manner. Servers with higher weights receive\n 130:\t\t new connections first than those with less weights, and servers\n 131:\t\t with higher weights get more connections than those with less\n 132:\t\t weights and servers with equal weights get equal connections.\n 133:\t\n 134:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 135:\t\t module, choose M here. If unsure, say N.\n 136:\t\n 137:\tconfig\tIP_VS_LC\n 138:\t\ttristate \"least-connection scheduling\"\n 139:\t\thelp\n 140:\t\t The least-connection scheduling algorithm directs network\n 141:\t\t connections to the server with the least number of active \n 142:\t\t connections.\n 143:\t\n 144:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 145:\t\t module, choose M here. If unsure, say N.\n 146:\t\n 147:\tconfig\tIP_VS_WLC\n 148:\t\ttristate \"weighted least-connection scheduling\"\n 149:\t\thelp\n 150:\t\t The weighted least-connection scheduling algorithm directs network\n 151:\t\t connections to the server with the least active connections\n 152:\t\t normalized by the server weight.\n 153:\t\n 154:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 155:\t\t module, choose M here. If unsure, say N.\n 156:\t\n 157:\tconfig IP_VS_FO\n 158:\t\t\ttristate \"weighted failover scheduling\"\n 159:\t\thelp\n 160:\t\t The weighted failover scheduling algorithm directs network\n 161:\t\t connections to the server with the highest weight that is\n 162:\t\t currently available.\n 163:\t\n 164:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 165:\t\t module, choose M here. If unsure, say N.\n 166:\t\n 167:\tconfig IP_VS_OVF\n 168:\t\ttristate \"weighted overflow scheduling\"\n 169:\t\thelp\n 170:\t\t The weighted overflow scheduling algorithm directs network\n 171:\t\t connections to the server with the highest weight that is\n 172:\t\t currently available and overflows to the next when active\n 173:\t\t connections exceed the node's weight.\n 174:\t\n 175:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 176:\t\t module, choose M here. If unsure, say N.\n 177:\t\n 178:\tconfig\tIP_VS_LBLC\n 179:\t\ttristate \"locality-based least-connection scheduling\"\n 180:\t\thelp\n" }
9/2	2026/09/07 22:10	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 14941 output: 36 thoughts: 387 Thoughts: Fuzzing Target Identification: IPVS Destination Overload Threshold Okay, let's break this down. IPVS is definitely a key component here, part of netfilter, and accessible through netlink interfaces, sockopt, etc., which is a good sign, especially considering its integration in QEMU/virt environments. The critical question: Is this thing reachable through syzkaller? Yep, syzkaller supports IPVS netlink and netfilter operations. Excellent. Now, we're talking about code that's potentially modifying the IPVS destination overload threshold logic and the underlying structure layout. I need to pinpoint the exact locations: - `ip_vs_bind_dest` and `ip_vs_unbind_dest` within `net/netfilter/ipvs/ip_vs_conn.c`. - `ip_vs_dest_update_overload`, `__ip_vs_dest_update_overload`, and `__ip_vs_update_dest` within `net/netfilter/ipvs/ip_vs_ctl.c`. - And the scheduler functions in the various scheduler files involved. Time to see if this is "WorthFuzzing". Considering that it touches executable networking, netfilter, and IPVS code that's reachable, the answer is a resounding "yes". So, the `WorthFuzzing` flag is set to `true`. Now for `FocusSymbols`. I need to be precise, zeroing in on the specific functions that are being modified or directly call the modified logic, and that are not ubiquitous. Let's see... In `ip_vs_conn.c`, we have: - `ip_vs_bind_dest` - `ip_vs_unbind_dest` And then in `ip_vs_ctl.c`: - `ip_vs_dest_update_overload` (This is exported and non-static, so promising!) - `__ip_vs_update_dest` (or any of its callers, `ip_vs_edit_dest` or `ip_vs_add_dest`.) Let's dive into `ip_vs_ctl.c` around `__ip_vs_update_dest`. That seems like the right area to concentrate on.
10/2	2026/09/07 22:10	tool	grepper	0m Args: { "Expression": "__ip_vs_update_dest", "PathPrefix": "net/netfilter/ipvs/" } Results: { "Output": "net/netfilter/ipvs/ip_vs_ctl.c=1344=static void\nnet/netfilter/ipvs/ip_vs_ctl.c:1345:__ip_vs_update_dest(struct ip_vs_service svc, struct ip_vs_dest dest,\nnet/netfilter/ipvs/ip_vs_ctl.c-1346-\t\t struct ip_vs_dest_user_kern udest, int add)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=1443=ip_vs_new_dest(struct ip_vs_service svc, struct ip_vs_dest_user_kern udest)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-1494-\tspin_lock_init(\u0026dest-\u003edst_lock);\nnet/netfilter/ipvs/ip_vs_ctl.c:1495:\t__ip_vs_update_dest(svc, dest, udest, 1);\nnet/netfilter/ipvs/ip_vs_ctl.c-1496-\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=1512=ip_vs_add_dest(struct ip_vs_service svc, struct ip_vs_dest_user_kern udest)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-1572-\t\telse\nnet/netfilter/ipvs/ip_vs_ctl.c:1573:\t\t\t__ip_vs_update_dest(svc, dest, udest, 1);\nnet/netfilter/ipvs/ip_vs_ctl.c-1574-\t} else {\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=1589=ip_vs_edit_dest(struct ip_vs_service svc, struct ip_vs_dest_user_kern *udest)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-1627-\nnet/netfilter/ipvs/ip_vs_ctl.c:1628:\t__ip_vs_update_dest(svc, dest, udest, 0);\nnet/netfilter/ipvs/ip_vs_ctl.c-1629-\n" }
11/2	2026/09/07 22:10	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 16431 output: 35 thoughts: 392 Thoughts: My Analysis of IPVS Scheduler Modifications Okay, let's dive into this. First, I need to verify which schedulers have been touched. My initial focus is on these twelve: `ip_vs_dh_schedule`, `ip_vs_fo_schedule`, `__ip_vs_lblc_schedule`, `__ip_vs_lblcr_schedule`, `ip_vs_lc_schedule`, `ip_vs_nq_schedule`, `ip_vs_ovf_schedule`, `ip_vs_rr_schedule`, `ip_vs_sed_schedule`, `ip_vs_twos_schedule`, `ip_vs_wlc_schedule`, and `ip_vs_wrr_schedule`. I'll need to look at the supporting functions as well: `ip_vs_dest_update_overload`, `ip_vs_bind_dest`, `ip_vs_unbind_dest`, `ip_vs_edit_dest`, and `ip_vs_add_dest`. Now, before I proceed with any further investigation, I need to check what configurations, if any, are needed. A quick look at the `Kconfig` for the IPVS core tells me that it depends on `INET` and `NETFILTER` and either `NF_CONNTRACK` or `NF_CONNTRACK=n`. That makes sense. I have to make sure these dependencies are properly handled. And of course, the schedulers themselves are enabled by configs as well, namely: `IP_VS_RR`, `IP_VS_WRR`, `IP_VS_LC`, `IP_VS_WLC`, `IP_VS_FO`, `IP_VS_OVF`, `IP_VS_LBLC`, `IP_VS_LBLCR`, `IP_VS_DH`, `IP_VS_SH`, `IP_VS_SED`, `IP_VS_NQ`, `IP_VS_TWOS`, and `IP_VS_MH`. I should also re-confirm that `NETFILTER` and `INET` are configured correctly and that there are no conflicts. To make sure I'm precise, I'll need to examine the `Kconfig` files more closely. I need to make sure I am accounting for everything.
12/2	2026/09/07 22:10	tool	grepper	0m Args: { "Expression": "config IP_VS_", "PathPrefix": "net/netfilter/ipvs/Kconfig" } Results: { "Output": "net/netfilter/ipvs/Kconfig=286=comment 'IPVS SH scheduler'\nnet/netfilter/ipvs/Kconfig-287-\nnet/netfilter/ipvs/Kconfig:288:config IP_VS_SH_TAB_BITS\nnet/netfilter/ipvs/Kconfig-289-\tint \"IPVS source hashing table size (the Nth power of 2)\"\n--\nnet/netfilter/ipvs/Kconfig=301=comment 'IPVS MH scheduler'\nnet/netfilter/ipvs/Kconfig-302-\nnet/netfilter/ipvs/Kconfig:303:config IP_VS_MH_TAB_INDEX\nnet/netfilter/ipvs/Kconfig-304-\tint \"IPVS maglev hashing table index of size (the prime numbers)\"\n" }
13/2	2026/09/07 22:10	llm	patch-evaluator	1m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 17558 output: 39 thoughts: 30 Thoughts: Here's my summary, as if I were thinking these thoughts: Examining the IPVS Configuration Options Alright, let's dive into the IPVS Kconfig file, specifically the section from lines 180 to 320 in `net/netfilter/ipvs/Kconfig`. I'm going to focus on what options are defined within that area. I'm probably looking at this to either understand a specific feature's configuration parameters, debug a build issue, or perhaps even analyze the conditional logic that governs which modules or features get enabled. My goal is to get a handle on what the user has the ability to enable or disable and to which other settings these features are dependent. Knowing this is critical, since a misconfiguration or misunderstanding can lead to operational instability.
14/2	2026/09/07 22:11	tool	read-file	0m Args: { "File": "net/netfilter/ipvs/Kconfig", "FirstLine": 180, "LineCount": 100 } Results: { "Contents": " 180:\t\thelp\n 181:\t\t The locality-based least-connection scheduling algorithm is for\n 182:\t\t destination IP load balancing. It is usually used in cache cluster.\n 183:\t\t This algorithm usually directs packet destined for an IP address to\n 184:\t\t its server if the server is alive and under load. If the server is\n 185:\t\t overloaded (its active connection numbers is larger than its weight)\n 186:\t\t and there is a server in its half load, then allocate the weighted\n 187:\t\t least-connection server to this IP address.\n 188:\t\n 189:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 190:\t\t module, choose M here. If unsure, say N.\n 191:\t\n 192:\tconfig IP_VS_LBLCR\n 193:\t\ttristate \"locality-based least-connection with replication scheduling\"\n 194:\t\thelp\n 195:\t\t The locality-based least-connection with replication scheduling\n 196:\t\t algorithm is also for destination IP load balancing. It is \n 197:\t\t usually used in cache cluster. It differs from the LBLC scheduling\n 198:\t\t as follows: the load balancer maintains mappings from a target\n 199:\t\t to a set of server nodes that can serve the target. Requests for\n 200:\t\t a target are assigned to the least-connection node in the target's\n 201:\t\t server set. If all the node in the server set are over loaded,\n 202:\t\t it picks up a least-connection node in the cluster and adds it\n 203:\t\t in the sever set for the target. If the server set has not been\n 204:\t\t modified for the specified time, the most loaded node is removed\n 205:\t\t from the server set, in order to avoid high degree of replication.\n 206:\t\n 207:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 208:\t\t module, choose M here. If unsure, say N.\n 209:\t\n 210:\tconfig\tIP_VS_DH\n 211:\t\ttristate \"destination hashing scheduling\"\n 212:\t\thelp\n 213:\t\t The destination hashing scheduling algorithm assigns network\n 214:\t\t connections to the servers through looking up a statically assigned\n 215:\t\t hash table by their destination IP addresses.\n 216:\t\n 217:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 218:\t\t module, choose M here. If unsure, say N.\n 219:\t\n 220:\tconfig\tIP_VS_SH\n 221:\t\ttristate \"source hashing scheduling\"\n 222:\t\thelp\n 223:\t\t The source hashing scheduling algorithm assigns network\n 224:\t\t connections to the servers through looking up a statically assigned\n 225:\t\t hash table by their source IP addresses.\n 226:\t\n 227:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 228:\t\t module, choose M here. If unsure, say N.\n 229:\t\n 230:\tconfig\tIP_VS_MH\n 231:\t\ttristate \"maglev hashing scheduling\"\n 232:\t\thelp\n 233:\t\t The maglev consistent hashing scheduling algorithm provides the\n 234:\t\t Google's Maglev hashing algorithm as a IPVS scheduler. It assigns\n 235:\t\t network connections to the servers through looking up a statically\n 236:\t\t assigned special hash table called the lookup table. Maglev hashing\n 237:\t\t is to assign a preference list of all the lookup table positions\n 238:\t\t to each destination.\n 239:\t\n 240:\t\t Through this operation, The maglev hashing gives an almost equal\n 241:\t\t share of the lookup table to each of the destinations and provides\n 242:\t\t minimal disruption by using the lookup table. When the set of\n 243:\t\t destinations changes, a connection will likely be sent to the same\n 244:\t\t destination as it was before.\n 245:\t\n 246:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 247:\t\t module, choose M here. If unsure, say N.\n 248:\t\n 249:\tconfig\tIP_VS_SED\n 250:\t\ttristate \"shortest expected delay scheduling\"\n 251:\t\thelp\n 252:\t\t The shortest expected delay scheduling algorithm assigns network\n 253:\t\t connections to the server with the shortest expected delay. The \n 254:\t\t expected delay that the job will experience is (Ci + 1) / Ui if \n 255:\t\t sent to the ith server, in which Ci is the number of connections\n 256:\t\t on the ith server and Ui is the fixed service rate (weight)\n 257:\t\t of the ith server.\n 258:\t\n 259:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 260:\t\t module, choose M here. If unsure, say N.\n 261:\t\n 262:\tconfig\tIP_VS_NQ\n 263:\t\ttristate \"never queue scheduling\"\n 264:\t\thelp\n 265:\t\t The never queue scheduling algorithm adopts a two-speed model.\n 266:\t\t When there is an idle server available, the job will be sent to\n 267:\t\t the idle server, instead of waiting for a fast one. When there\n 268:\t\t is no idle server available, the job will be sent to the server\n 269:\t\t that minimize its expected delay (The Shortest Expected Delay\n 270:\t\t scheduling algorithm).\n 271:\t\n 272:\t\t If you want to compile it in kernel, say Y. To compile it as a\n 273:\t\t module, choose M here. If unsure, say N.\n 274:\t\n 275:\tconfig\tIP_VS_TWOS\n 276:\t\ttristate \"weighted random twos choice least-connection scheduling\"\n 277:\t\thelp\n 278:\t\t The weighted random twos choice least-connection scheduling\n 279:\t\t algorithm picks two random real servers and directs network\n" }
15/2	2026/09/07 22:11	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 19458 output: 256 thoughts: 720 Thoughts: IPVS Overload Handling Patch Review Okay, let's break this down. First, I need to meticulously examine the changes to the IPVS core. It appears we're addressing the overload mechanism, and the removal of `IP_VS_DEST_F_OVERLOAD` from the `flags` field in `include/net/ip_vs.h` immediately piques my interest. It implies a shift in how overload state is managed – likely, we're moving towards a more explicit threshold-based approach, confirmed by the `READ_ONCE(dest->l_threshold_val)` check and the addition/reordering of `u_threshold_val` and `l_threshold_val` in `struct ip_vs_dest`. That struct reorganization deserves a closer look to see if there are any subtle alignment issues that could crop up, even with `READ_ONCE` in play. Next, the connection tracking side in `ip_vs_conn.c` is key. `ip_vs_bind_dest` and `ip_vs_unbind_dest` now explicitly call `ip_vs_dest_update_overload` based on comparisons with the new threshold values, `u_threshold_val` and `l_threshold_val`, respectively. This is the heart of the logic, and I need to fully understand how these thresholds are being set and used to toggle the overload state, and if there are edge cases in the connections life cycle. The control plane changes in `ip_vs_ctl.c` with the new update functions are going to be important too – specifically `__ip_vs_dest_update_overload`, `ip_vs_dest_update_overload`, and `__ip_vs_update_dest`. I need to track how they are triggered, to verify they fit with the threshold changes and the scheduler logic. Finally, the scheduler integration is crucial. I see changes in many of the schedulers, specifically: `ip_vs_dh_schedule`, `ip_vs_fo_schedule`, `__ip_vs_lblc_schedule`, `__ip_vs_lblcr_schedule`, `ip_vs_lc_schedule`, `is_unavailable` in mh and sh, `ip_vs_nq_schedule`, `ip_vs_ovf_schedule`, `ip_vs_rr_schedule`, `ip_vs_sed_schedule`, `ip_vs_twos_schedule`, `ip_vs_wlc_schedule`, `ip_vs_wrr_schedule`. This is where the rubber meets the road. I need to understand how the overload state affects the scheduling decisions. For instance, is `is_unavailable` being used in the overload path? I need to verify that each scheduler is behaving correctly and that no unexpected behavior, such as unnecessary back-off, is introduced. Given the structural changes and logic shift, I need to specify these FocusSymbols to be targeted for fuzzing: `ip_vs_dest_update_overload`, `ip_vs_bind_dest`, `ip_vs_unbind_dest`, `__ip_vs_update_dest`, `ip_vs_add_dest`, `ip_vs_edit_dest`, `ip_vs_dh_schedule`, `ip_vs_fo_schedule`, `ip_vs_lc_schedule`, `ip_vs_ovf_schedule`, `ip_vs_rr_schedule`, `ip_vs_sed_schedule`, `ip_vs_twos_schedule`, `ip_vs_wlc_schedule`, and `ip_vs_wrr_schedule`. The configuration dependencies appear to be the standard IPVS stack: `IP_VS`, `NETFILTER`, and `INET`. Nothing unexpected there. Ultimately, I'm confident that these changes warrant thorough fuzzing. The patch significantly alters data structure layout and the threshold/overload state logic, impacting IPVS connection tracking, control plane destination updating, and scheduling algorithms. Therefore, the reasoning for `set-results` will clearly explain this fact, specify the focus symbols, and include the enable configurations. This covers everything. Let's proceed.
16/2	2026/09/07 22:11	tool	set-results	0m Args: { "EnableConfigs": [ "IP_VS", "NETFILTER", "INET" ], "FocusSymbols": [ "ip_vs_dest_update_overload", "ip_vs_bind_dest", "ip_vs_unbind_dest", "__ip_vs_update_dest", "ip_vs_edit_dest", "ip_vs_add_dest", "ip_vs_rr_schedule", "ip_vs_wrr_schedule", "ip_vs_wlc_schedule", "ip_vs_lc_schedule", "ip_vs_fo_schedule", "ip_vs_ovf_schedule", "ip_vs_twos_schedule" ], "Reasoning": "The patch modifies the destination overload tracking logic and destination structure layout in the IPVS (IP Virtual Server) subsystem. It updates connection binding and unbinding thresholds, control plane destination updates, and scheduler overload evaluation across IPVS algorithms. These are reachable, executable network paths that should be fuzzed for race conditions, arithmetic or state handling bugs, and threshold edge cases.", "WorthFuzzing": true } Results: { "EnableConfigs": [ "IP_VS", "NETFILTER", "INET" ], "FocusSymbols": [ "ip_vs_dest_update_overload", "ip_vs_bind_dest", "ip_vs_unbind_dest", "__ip_vs_update_dest", "ip_vs_edit_dest", "ip_vs_add_dest", "ip_vs_rr_schedule", "ip_vs_wrr_schedule", "ip_vs_wlc_schedule", "ip_vs_lc_schedule", "ip_vs_fo_schedule", "ip_vs_ovf_schedule", "ip_vs_twos_schedule" ], "Reasoning": "The patch modifies the destination overload tracking logic and destination structure layout in the IPVS (IP Virtual Server) subsystem. It updates connection binding and unbinding thresholds, control plane destination updates, and scheduler overload evaluation across IPVS algorithms. These are reachable, executable network paths that should be fuzzed for race conditions, arithmetic or state handling bugs, and threshold edge cases.", "WorthFuzzing": true }
17/1	2026/09/07 22:11	action	If	0m Args: { "WorthFuzzing": true } Results: null
18/2	2026/09/07 22:11	agent	kmsan-evaluator	0m Model: core Args: null Results: { "KMSANReasoning": "The patch reorganizes fields in `struct ip_vs_dest` for better cacheline utilization and refactors the destination overload status tracking to use `l_threshold_val` / `u_threshold_val` instead of `dest-\u003eflags` with `IP_VS_DEST_F_OVERLOAD`.\n\nAll `struct ip_vs_dest` instances are zero-allocated with `kzalloc_obj()` and their threshold fields are properly initialized upon creation. The structure itself is not copied to userspace as a raw blob; userspace queries serialize individual fields or use zeroed intermediate structures (`memset` in `__ip_vs_get_dest_entries` and individual Netlink attributes in `ip_vs_genl_fill_dest`). No uninitialized memory is read, copied to userspace, or branched upon.\n\nBecause the changes introduce no uninitialized memory risks, a dedicated KMSAN fuzzing session is not warranted. Standard KASAN fuzzing is sufficient.", "NeedsKMSAN": false } Instruction: You are an expert Linux kernel security engineer specializing in kernel memory error detectors (KASAN and KMSAN). Your job is to review the provided patch series and determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer) fuzzing session in addition to standard KASAN fuzzing. CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN: - Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable a comprehensive suite of debugging tools and sanitizers, including KASAN (out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP (locking bugs and deadlocks), UB-sanitizers, and memory corruption checks. - KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap, or page allocations) and kernel-to-user memory info-leaks. Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN, LOCKDEP, OR OTHER STANDARD BUG DETECTORS. A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks that are detected ONLY by KMSAN. Look holistically at the patch series and surrounding code. Even if no direct uninitialized field accesses or new buffer allocations are added in the diff itself, a patch may alter control flow, bounds checking, or data length calculations in ways that change how the rest of the code operates on existing buffers (e.g. allowing uninitialized stack/heap memory to be read, copied to user space, or used in control flow). Do not hesitate to use your code access tools to inspect the surrounding code, called functions, and callers. Set NeedsKMSAN=true ONLY IF the patch introduces or modifies: 1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb attributes, ioctl output arguments, socket options, or BPF buffers) where fields or structure padding might not be fully initialized/zeroed. 2. Conditional logic or branching that depends on potentially uninitialized variables or struct fields. 3. Allocation or initialization of complex data structures where uninitialized fields could be read later in reachable code paths. 4. Bounds checks, lengths, or logic in a way that allows surrounding code to access uninitialized bytes of existing buffers. Set NeedsKMSAN=false IF: - The code changes primarily risk out-of-bounds access, array overflows, NULL pointer dereferences, locking deadlocks, or use-after-free bugs (these are already caught by KASAN, LOCKDEP, or standard bug detectors). - All stack/heap structures touched or introduced by the patch are fully zeroed or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied. - The patch does not introduce any risk of uninitialized memory usage or info-leaks. Use your code access tools to inspect the surrounding code if necessary, then provide detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch. Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit a029c18539e2bd4393bb8736df0003e422cb7c9b Author: syz-cluster <triage@syzkaller.com> Date: Mon Sep 7 22:10:16 2026 +0000 syz-cluster: applied patch under review diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h index 32fde731bceb7..9a83bff32569d 100644 --- a/include/net/ip_vs.h +++ b/include/net/ip_vs.h @@ -36,9 +36,6 @@ #define IP_VS_HDR_INVERSE 1 #define IP_VS_HDR_ICMP 2 -/* Destination Server Flags / -#define IP_VS_DEST_F_OVERLOAD 0x0002 / server is overloaded / - / Destination Server Config Flags / #define IP_VS_DEST_CF_AVAILABLE 0x0001 / server is available / @@ -973,32 +970,43 @@ struct ip_vs_dest_dst { and so on. / struct ip_vs_dest { + / Cacheline for hash table nodes - read-mostly / + struct list_head n_list; / for the dests in the service / struct hlist_node d_list; / for table with all the dests / - u16 af; / address family / - __be16 port; / port number of the server / - union nf_inet_addr addr; / IP address of the server / - volatile unsigned int flags; / dest status flags / - atomic_t conn_flags; / flags to copy to conn / atomic_t weight; / server weight / - unsigned long cflags; / config flags / atomic_t last_weight; / server latest weight / + + / connection thresholds / + u32 l_threshold_val;/ used lower threshold / + u32 u_threshold_val;/ used upper threshold / + / 32/48 / + u32 l_threshold; / lower threshold / + u32 u_threshold; / upper threshold / + + unsigned long cflags; / config flags / + + / 44/64 / + atomic_t conn_flags; / flags to copy to conn / + __u16 tun_type; / tunnel type / __be16 tun_port; / tunnel port / __u16 tun_flags; / tunnel flags / - refcount_t refcnt; / reference counter / - struct ip_vs_stats stats; / statistics / - unsigned long idle_start; / start time, jiffies / + u16 af; / address family / + __be16 port; / port number of the server / + / 60/80 / + union nf_inet_addr addr; / IP address of the server / - / connection counters and thresholds / - atomic_t activeconns; / active connections / + / connection counters / atomic_t totalconns; / total connections / + atomic_t activeconns; / active connections / atomic_t persistconns; / persistent connections / - __u32 u_threshold; / upper threshold / - __u32 l_threshold; / lower threshold / - __u32 l_threshold_val;/ used lower threshold / + + refcount_t refcnt; / reference counter / + struct ip_vs_stats stats; / statistics / + unsigned long idle_start; / start time, jiffies / / for destination cache / spinlock_t dst_lock; / lock of dst_cache / @@ -1915,7 +1923,13 @@ static inline void ip_vs_dest_put_and_free(struct ip_vs_dest dest) kfree(dest); } -void ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode); +void ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload); + +/* Check if dest is in overloaded state / +static inline bool ip_vs_dest_is_overloaded(const struct ip_vs_dest dest) +{ + return READ_ONCE(dest->l_threshold_val); +} /* IPVS sync daemon data and function prototypes * (from ip_vs_sync.c) diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c index 6fa3e1dc534c3..5348c2f49b64e 100644 --- a/net/netfilter/ipvs/ip_vs_conn.c +++ b/net/netfilter/ipvs/ip_vs_conn.c @@ -1150,8 +1150,8 @@ ip_vs_bind_dest(struct ip_vs_conn cp, struct ip_vs_dest dest) if (!(flags & IP_VS_CONN_F_INACTIVE)) atomic_inc(&dest->activeconns); tc = atomic_inc_return(&dest->totalconns); - if (tc == READ_ONCE(dest->u_threshold)) - ip_vs_dest_update_overload(dest, 1); + if (tc >= READ_ONCE(dest->u_threshold_val)) + ip_vs_dest_update_overload(dest, true); } else { /* It is a persistent connection/template, so increase the persistent connection counter / @@ -1243,8 +1243,8 @@ static inline void ip_vs_unbind_dest(struct ip_vs_conn cp) if (!(cp->flags & IP_VS_CONN_F_INACTIVE)) atomic_dec(&dest->activeconns); tc = atomic_fetch_dec(&dest->totalconns); - if (tc == READ_ONCE(dest->l_threshold_val)) - ip_vs_dest_update_overload(dest, -1); + if (tc <= READ_ONCE(dest->l_threshold_val)) + ip_vs_dest_update_overload(dest, false); } else { /* It is a persistent connection/template, so decrease the persistent connection counter / diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index 4c1c739446b76..3003547dcabe5 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -1309,32 +1309,32 @@ void ip_vs_stats_free(struct ip_vs_stats stats) * - conns reach u_threshold and exceed it: set the flag * - conns go below l_threshold (or 75% of u_threshold): clear the flag / -static void __ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode) +static void __ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload) { int conns; u32 l, u; lockdep_assert_held(&dest->dst_lock); u = READ_ONCE(dest->u_threshold); - if (!u) - goto unset; - l = READ_ONCE(dest->l_threshold_val); - conns = atomic_read(&dest->totalconns); - if (conns >= (mode > 0 ? l : u)) { - dest->flags \|= IP_VS_DEST_F_OVERLOAD; - return; + if (u) { + / Low threshold defaults to 75% of upper threshold / + l = READ_ONCE(dest->l_threshold) ? : (u - (u >> 2)); + conns = atomic_read(&dest->totalconns); + if (conns >= (overload ? l : u)) { + WRITE_ONCE(dest->u_threshold_val, INT_MAX); + WRITE_ONCE(dest->l_threshold_val, l); + return; + } } - if (conns >= (mode < 0 ? u : l)) - return; -unset: - dest->flags &= ~IP_VS_DEST_F_OVERLOAD; + WRITE_ONCE(dest->u_threshold_val, u ? : INT_MAX); + WRITE_ONCE(dest->l_threshold_val, 0); } -void ip_vs_dest_update_overload(struct ip_vs_dest dest, int mode) +void ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload) { spin_lock_bh(&dest->dst_lock); - __ip_vs_dest_update_overload(dest, mode); + __ip_vs_dest_update_overload(dest, overload); spin_unlock_bh(&dest->dst_lock); } @@ -1406,15 +1406,13 @@ __ip_vs_update_dest(struct ip_vs_service svc, struct ip_vs_dest dest, if (READ_ONCE(dest->u_threshold) != udest->u_threshold \|\| READ_ONCE(dest->l_threshold) != udest->l_threshold) { + bool overload; + spin_lock_bh(&dest->dst_lock); WRITE_ONCE(dest->u_threshold, udest->u_threshold); WRITE_ONCE(dest->l_threshold, udest->l_threshold); - / Low threshold defaults to 75% of upper threshold / - WRITE_ONCE(dest->l_threshold_val, - udest->l_threshold ? : - (udest->u_threshold - - (udest->u_threshold >> 2))); - __ip_vs_dest_update_overload(dest, 0); + overload = ip_vs_dest_is_overloaded(dest); + __ip_vs_dest_update_overload(dest, overload); spin_unlock_bh(&dest->dst_lock); } diff --git a/net/netfilter/ipvs/ip_vs_dh.c b/net/netfilter/ipvs/ip_vs_dh.c index 43abed7a26a6a..95e52950adbb7 100644 --- a/net/netfilter/ipvs/ip_vs_dh.c +++ b/net/netfilter/ipvs/ip_vs_dh.c @@ -195,16 +195,6 @@ static int ip_vs_dh_dest_changed(struct ip_vs_service svc, } -/* - * If the dest flags is set with IP_VS_DEST_F_OVERLOAD, - * consider that the server is overloaded here. - / -static inline int is_overloaded(struct ip_vs_dest dest) -{ - return dest->flags & IP_VS_DEST_F_OVERLOAD; -} - - /* * Destination hashing scheduling / @@ -219,10 +209,8 @@ ip_vs_dh_schedule(struct ip_vs_service svc, const struct sk_buff skb, s = (struct ip_vs_dh_state ) svc->sched_data; dest = ip_vs_dh_get(svc->af, s, &iph->daddr); - if (!dest \|\| - !(dest->cflags & IP_VS_DEST_CF_AVAILABLE) - \|\| atomic_read(&dest->weight) <= 0 - \|\| is_overloaded(dest)) { + if (!dest \|\| atomic_read(&dest->weight) <= 0 \|\| + ip_vs_dest_is_overloaded(dest)) { ip_vs_scheduler_err(svc, "no destination available"); return NULL; } diff --git a/net/netfilter/ipvs/ip_vs_fo.c b/net/netfilter/ipvs/ip_vs_fo.c index d657b47c6511f..e07fa33f6d527 100644 --- a/net/netfilter/ipvs/ip_vs_fo.c +++ b/net/netfilter/ipvs/ip_vs_fo.c @@ -29,7 +29,7 @@ ip_vs_fo_schedule(struct ip_vs_service svc, const struct sk_buff skb, * Find virtual server with highest weight and send it traffic / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) > hw) { hweight = dest; hw = atomic_read(&dest->weight); diff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c index 693bcc82ccb77..bff109c1c959b 100644 --- a/net/netfilter/ipvs/ip_vs_lblc.c +++ b/net/netfilter/ipvs/ip_vs_lblc.c @@ -414,7 +414,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service svc) * new connection. / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; if (atomic_read(&dest->weight) > 0) { least = dest; @@ -429,7 +429,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service svc) / nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_dest_conn_overhead(dest); diff --git a/net/netfilter/ipvs/ip_vs_lblcr.c b/net/netfilter/ipvs/ip_vs_lblcr.c index f53f05ceea36f..c2853e07e7872 100644 --- a/net/netfilter/ipvs/ip_vs_lblcr.c +++ b/net/netfilter/ipvs/ip_vs_lblcr.c @@ -166,7 +166,7 @@ static inline struct ip_vs_dest ip_vs_dest_set_min(struct ip_vs_dest_set set) / select the first destination server, whose weight > 0 / list_for_each_entry_rcu(e, &set->list, list) { least = e->dest; - if (least->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(least)) continue; if ((atomic_read(&least->weight) > 0) && @@ -181,7 +181,7 @@ static inline struct ip_vs_dest ip_vs_dest_set_min(struct ip_vs_dest_set set) nextstage: list_for_each_entry_continue_rcu(e, &set->list, list) { dest = e->dest; - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_dest_conn_overhead(dest); @@ -577,7 +577,7 @@ __ip_vs_lblcr_schedule(struct ip_vs_service svc) * new connection. / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; if (atomic_read(&dest->weight) > 0) { @@ -593,7 +593,7 @@ __ip_vs_lblcr_schedule(struct ip_vs_service svc) / nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_dest_conn_overhead(dest); diff --git a/net/netfilter/ipvs/ip_vs_lc.c b/net/netfilter/ipvs/ip_vs_lc.c index 18b976a7c4d20..9002f491bff68 100644 --- a/net/netfilter/ipvs/ip_vs_lc.c +++ b/net/netfilter/ipvs/ip_vs_lc.c @@ -38,7 +38,7 @@ ip_vs_lc_schedule(struct ip_vs_service svc, const struct sk_buff skb, / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if ((dest->flags & IP_VS_DEST_F_OVERLOAD) \|\| + if (ip_vs_dest_is_overloaded(dest) \|\| atomic_read(&dest->weight) == 0) continue; doh = ip_vs_dest_conn_overhead(dest); diff --git a/net/netfilter/ipvs/ip_vs_mh.c b/net/netfilter/ipvs/ip_vs_mh.c index 020863047562d..d70b23aec5fec 100644 --- a/net/netfilter/ipvs/ip_vs_mh.c +++ b/net/netfilter/ipvs/ip_vs_mh.c @@ -80,7 +80,7 @@ static inline void generate_hash_secret(hsiphash_key_t hash1, static inline bool is_unavailable(struct ip_vs_dest dest) { return atomic_read(&dest->weight) <= 0 \|\| - dest->flags & IP_VS_DEST_F_OVERLOAD; + ip_vs_dest_is_overloaded(dest); } /* Returns hash value for IPVS MH entry / diff --git a/net/netfilter/ipvs/ip_vs_nq.c b/net/netfilter/ipvs/ip_vs_nq.c index ada158c610ce1..7cc28902086e7 100644 --- a/net/netfilter/ipvs/ip_vs_nq.c +++ b/net/netfilter/ipvs/ip_vs_nq.c @@ -72,7 +72,7 @@ ip_vs_nq_schedule(struct ip_vs_service svc, const struct sk_buff skb, list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD \|\| + if (ip_vs_dest_is_overloaded(dest) \|\| !atomic_read(&dest->weight)) continue; diff --git a/net/netfilter/ipvs/ip_vs_ovf.c b/net/netfilter/ipvs/ip_vs_ovf.c index c5c67df80a0b3..eaa3a7ae6efa6 100644 --- a/net/netfilter/ipvs/ip_vs_ovf.c +++ b/net/netfilter/ipvs/ip_vs_ovf.c @@ -33,7 +33,7 @@ ip_vs_ovf_schedule(struct ip_vs_service svc, const struct sk_buff skb, / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { w = atomic_read(&dest->weight); - if ((dest->flags & IP_VS_DEST_F_OVERLOAD) \|\| + if (ip_vs_dest_is_overloaded(dest) \|\| atomic_read(&dest->activeconns) > w \|\| w == 0) continue; diff --git a/net/netfilter/ipvs/ip_vs_rr.c b/net/netfilter/ipvs/ip_vs_rr.c index 4125ee561cdc3..bd17cdd092f5f 100644 --- a/net/netfilter/ipvs/ip_vs_rr.c +++ b/net/netfilter/ipvs/ip_vs_rr.c @@ -66,7 +66,7 @@ ip_vs_rr_schedule(struct ip_vs_service svc, const struct sk_buff skb, list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) > 0) /* HIT / goto out; diff --git a/net/netfilter/ipvs/ip_vs_sed.c b/net/netfilter/ipvs/ip_vs_sed.c index 245a323c84cd3..7925f4d28fce9 100644 --- a/net/netfilter/ipvs/ip_vs_sed.c +++ b/net/netfilter/ipvs/ip_vs_sed.c @@ -75,7 +75,7 @@ ip_vs_sed_schedule(struct ip_vs_service svc, const struct sk_buff skb, / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) > 0) { least = dest; loh = ip_vs_sed_dest_overhead(least); @@ -90,7 +90,7 @@ ip_vs_sed_schedule(struct ip_vs_service svc, const struct sk_buff skb, / nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_sed_dest_overhead(dest); if ((__s64)loh atomic_read(&dest->weight) > diff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c index cd67066e3b261..c24dd5cb7e478 100644 --- a/net/netfilter/ipvs/ip_vs_sh.c +++ b/net/netfilter/ipvs/ip_vs_sh.c @@ -73,7 +73,7 @@ struct ip_vs_sh_state { static inline bool is_unavailable(struct ip_vs_dest dest) { return atomic_read(&dest->weight) <= 0 \|\| - dest->flags & IP_VS_DEST_F_OVERLOAD; + ip_vs_dest_is_overloaded(dest); } / diff --git a/net/netfilter/ipvs/ip_vs_twos.c b/net/netfilter/ipvs/ip_vs_twos.c index dbb7f5fd4688a..86186122a1f01 100644 --- a/net/netfilter/ipvs/ip_vs_twos.c +++ b/net/netfilter/ipvs/ip_vs_twos.c @@ -52,7 +52,7 @@ static struct ip_vs_dest ip_vs_twos_schedule(struct ip_vs_service svc, /* Generate a random weight between [0,sum of all weights) / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD)) { + if (!ip_vs_dest_is_overloaded(dest)) { weight = atomic_read(&dest->weight); if (weight > 0) { total_weight += weight; @@ -75,7 +75,7 @@ static struct ip_vs_dest ip_vs_twos_schedule(struct ip_vs_service svc, / Pick two weighted servers / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; weight = atomic_read(&dest->weight); diff --git a/net/netfilter/ipvs/ip_vs_wlc.c b/net/netfilter/ipvs/ip_vs_wlc.c index 9da445ca09a14..08e9e22f72bf8 100644 --- a/net/netfilter/ipvs/ip_vs_wlc.c +++ b/net/netfilter/ipvs/ip_vs_wlc.c @@ -47,7 +47,7 @@ ip_vs_wlc_schedule(struct ip_vs_service svc, const struct sk_buff skb, / list_for_each_entry_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) > 0) { least = dest; loh = ip_vs_dest_conn_overhead(least); @@ -62,7 +62,7 @@ ip_vs_wlc_schedule(struct ip_vs_service svc, const struct sk_buff skb, / nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (dest->flags & IP_VS_DEST_F_OVERLOAD) + if (ip_vs_dest_is_overloaded(dest)) continue; doh = ip_vs_dest_conn_overhead(dest); if ((__s64)loh atomic_read(&dest->weight) > diff --git a/net/netfilter/ipvs/ip_vs_wrr.c b/net/netfilter/ipvs/ip_vs_wrr.c index 2dcff1040da52..fad69bae5a22b 100644 --- a/net/netfilter/ipvs/ip_vs_wrr.c +++ b/net/netfilter/ipvs/ip_vs_wrr.c @@ -176,7 +176,7 @@ ip_vs_wrr_schedule(struct ip_vs_service svc, const struct sk_buff skb, list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && + if (!ip_vs_dest_is_overloaded(dest) && atomic_read(&dest->weight) >= mark->cw) goto found; if (dest == stop)
19/3	2026/09/07 22:11	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 9352 output: 65 thoughts: 558 Thoughts: Analyzing the IPVS Patch for Uninitialized Memory Risks Okay, let's dive into this patch and assess the potential for uninitialized memory exposure, specifically with an eye towards whether a KMSAN fuzzing session is warranted. My initial focus is on the `struct ip_vs_dest` and how its fields are handled, especially after these changes. First, the core changes. The `#define IP_VS_DEST_F_OVERLOAD` is gone, which suggests a shift away from bitfields. The `struct ip_vs_dest` itself has been reorganized, removing the `volatile unsigned int flags` and reordering for cacheline alignment and packing. That's a standard optimization, but the addition of `u32 u_threshold_val` and the inline helper `ip_vs_dest_is_overloaded()` are key. The overload logic seems to be now based entirely on these threshold values (`l_threshold_val` and `u_threshold_val`). The `ip_vs_dest_update_overload` signature changed too. This is all good, clean code, but it needs to be understood. Looking at the code utilizing the structure, specifically `ip_vs_conn.c`, we see the overload logic in `ip_vs_bind_dest` and `ip_vs_unbind_dest`. The comparisons against `READ_ONCE(dest->u_threshold_val)` and `READ_ONCE(dest->l_threshold_val)` and subsequent calls to `ip_vs_dest_update_overload` are clear implementations of the new overload mechanism. The definition of the thresholds are handled in `ip_vs_ctl.c`, and the new functions are used to determine overload by reading the respective thresholds. The crucial next step is to understand how `struct ip_vs_dest` is allocated, initialized, and, most importantly, if any of its contents are ever copied to user space. If we are passing this structure into user-space, a security bug is introduced if there is any memory leak from uninitialized memory. This is where `grepper` will come in handy. I'll search for allocations of `ip_vs_dest` and any instances where its data is exposed via `getsockopt`, netlink, or any other means of communicating information to user space. My assumption is that the data will be exposed to user space, so that is the key. Then I need to investigate if there is any initialization. My suspicion is this will be a good candidate for fuzzing, depending on how this struct is handled.
20/3	2026/09/07 22:11	tool	grepper	0m Args: { "Expression": "kzalloc.ip_vs_dest\|ip_vs_dest_new\|ip_vs_genl_dump_dest\|ip_vs_genl_get_dest", "PathPrefix": "net/netfilter/ipvs" } Results:* { "Output": "net/netfilter/ipvs/ip_vs_ctl.c=1443=ip_vs_new_dest(struct ip_vs_service svc, struct ip_vs_dest_user_kern udest)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-1467-\nnet/netfilter/ipvs/ip_vs_ctl.c:1468:\tdest = kzalloc_obj(struct ip_vs_dest);\nnet/netfilter/ipvs/ip_vs_ctl.c-1469-\tif (dest == NULL)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=4305=static int ip_vs_genl_fill_dest(struct sk_buff skb, struct ip_vs_dest dest)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-4353-\nnet/netfilter/ipvs/ip_vs_ctl.c:4354:static int ip_vs_genl_dump_dest(struct sk_buff skb, struct ip_vs_dest dest,\nnet/netfilter/ipvs/ip_vs_ctl.c-4355-\t\t\t\tstruct netlink_callback cb)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-4375-\nnet/netfilter/ipvs/ip_vs_ctl.c:4376:static int ip_vs_genl_dump_dests(struct sk_buff skb,\nnet/netfilter/ipvs/ip_vs_ctl.c-4377-\t\t\t\t struct netlink_callback *cb)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-4401-\t\t\tcontinue;\nnet/netfilter/ipvs/ip_vs_ctl.c:4402:\t\tif (ip_vs_genl_dump_dest(skb, dest, cb) \u003c 0) {\nnet/netfilter/ipvs/ip_vs_ctl.c-4403-\t\t\tidx--;\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=4914=static const struct genl_small_ops ip_vs_genl_ops[] = {\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-4961-\t\t.flags\t= GENL_ADMIN_PERM,\nnet/netfilter/ipvs/ip_vs_ctl.c:4962:\t\t.dumpit\t= ip_vs_genl_dump_dests,\nnet/netfilter/ipvs/ip_vs_ctl.c-4963-\t},\n" }
21/3	2026/09/07 22:11	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 11179 output: 44 thoughts: 43 Thoughts: Okay, let's dive into this. Here's my thought process on the matter: Digging into the `ip_vs_ctl.c` Kernel Code Right, so I'm thinking about the way these destination and socket option functionalities are handled within the IP Virtual Server (IPVS) code, specifically around `ip_vs_ctl.c`. I need to zero in on potential areas where data might be incorrectly copied or handled. My initial focus will be on the `ip_vs_new_dest` and `ip_vs_genl_fill_dest` functions. I'll need to meticulously examine how data is fetched or placed in there, because incorrect copying in those areas could manifest in strange ways, and those functions look like likely places. However, I'm not going to stop there. I also need to broaden the scope and be sure I cover any other getsockopt copying code within `ip_vs_ctl.c` that could also lead to issues. It's best to be thorough at this stage. I'll review those sections to see if they're relevant, too.
22/3	2026/09/07 22:12	tool	read-file	0m Args: { "File": "net/netfilter/ipvs/ip_vs_ctl.c", "FirstLine": 1460, "LineCount": 40 } Results: { "Contents": "1460:\t\t} else\n1461:\t#endif\n1462:\t\t{\n1463:\t\t\tatype = inet_addr_type(svc-\u003eipvs-\u003enet, udest-\u003eaddr.ip);\n1464:\t\t\tif (atype != RTN_LOCAL \u0026\u0026 atype != RTN_UNICAST)\n1465:\t\t\t\treturn -EINVAL;\n1466:\t\t}\n1467:\t\n1468:\t\tdest = kzalloc_obj(struct ip_vs_dest);\n1469:\t\tif (dest == NULL)\n1470:\t\t\treturn -ENOMEM;\n1471:\t\n1472:\t\tret = ip_vs_stats_init_alloc(\u0026dest-\u003estats);\n1473:\t\tif (ret \u003c 0)\n1474:\t\t\tgoto err_alloc;\n1475:\t\n1476:\t\tret = ip_vs_start_estimator(svc-\u003eipvs, \u0026dest-\u003estats);\n1477:\t\tif (ret \u003c 0)\n1478:\t\t\tgoto err_stats;\n1479:\t\n1480:\t\tdest-\u003eaf = udest-\u003eaf;\n1481:\t\tdest-\u003eprotocol = svc-\u003eprotocol;\n1482:\t\tdest-\u003evaddr = svc-\u003eaddr;\n1483:\t\tdest-\u003evport = svc-\u003eport;\n1484:\t\tdest-\u003evfwmark = svc-\u003efwmark;\n1485:\t\tip_vs_addr_copy(udest-\u003eaf, \u0026dest-\u003eaddr, \u0026udest-\u003eaddr);\n1486:\t\tdest-\u003eport = udest-\u003eport;\n1487:\t\n1488:\t\tatomic_set(\u0026dest-\u003eactiveconns, 0);\n1489:\t\tatomic_set(\u0026dest-\u003etotalconns, 0);\n1490:\t\tatomic_set(\u0026dest-\u003epersistconns, 0);\n1491:\t\trefcount_set(\u0026dest-\u003erefcnt, 1);\n1492:\t\n1493:\t\tINIT_HLIST_NODE(\u0026dest-\u003ed_list);\n1494:\t\tspin_lock_init(\u0026dest-\u003edst_lock);\n1495:\t\t__ip_vs_update_dest(svc, dest, udest, 1);\n1496:\t\n1497:\t\treturn 0;\n1498:\t\n1499:\terr_stats:\n" }
23/3	2026/09/07 22:12	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 12117 output: 54 thoughts: 35 Thoughts: Okay, here's my interpretation of those thoughts, presented as a personal thought process, as requested: Diving Deeper into IPVS Destination Handling Alright, given the context, I think it's time to dig into the nitty-gritty of how IPVS manages destination entries. I'm going to shift my focus to those core functions – `ip_vs_genl_fill_dest` and `ip_vs_copy_dest_entry`. I want to really understand the data structures involved and how they're being populated and modified. The `getsockopt` handlers are also relevant and need a closer look because they represent external access to the destination data. I need to see how they interact with `ip_vs_genl_fill_dest` and `ip_vs_copy_dest_entry`, ensuring consistency and that no unexpected information leaks occur through these handlers. I need to identify potential race conditions or concurrency issues in manipulating these destination entries. Perhaps there are data access or locking subtleties in the `getsockopt` handler that are causing a problem. I'll need to trace the data flow and look for potential weaknesses or vulnerabilities.
24/3	2026/09/07 22:12	tool	grepper	0m Args: { "Expression": "ip_vs_dest_entry\|ip_vs_genl_fill_dest\|ip_vs_get_dests", "PathPrefix": "net/netfilter/ipvs" } Results: { "Output": "net/netfilter/ipvs/ip_vs_ctl.c=3680=static inline int\nnet/netfilter/ipvs/ip_vs_ctl.c:3681:__ip_vs_get_dest_entries(struct netns_ipvs ipvs, const struct ip_vs_get_dests get,\nnet/netfilter/ipvs/ip_vs_ctl.c:3682:\t\t\t struct ip_vs_get_dests __user uptr)\nnet/netfilter/ipvs/ip_vs_ctl.c-3683-{\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-3698-\t\tstruct ip_vs_dest dest;\nnet/netfilter/ipvs/ip_vs_ctl.c:3699:\t\tstruct ip_vs_dest_entry entry;\nnet/netfilter/ipvs/ip_vs_ctl.c-3700-\t\tstruct ip_vs_kstats kstats;\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=3757=static const unsigned char get_arglen[CMDID(IP_VS_SO_GET_MAX) + 1] = {\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-3761-\t[CMDID(IP_VS_SO_GET_SERVICE)] = sizeof(struct ip_vs_service_entry),\nnet/netfilter/ipvs/ip_vs_ctl.c:3762:\t[CMDID(IP_VS_SO_GET_DESTS)] = sizeof(struct ip_vs_get_dests),\nnet/netfilter/ipvs/ip_vs_ctl.c-3763-\t[CMDID(IP_VS_SO_GET_TIMEOUT)] = sizeof(struct ip_vs_timeout_user),\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=3767=union ip_vs_get_arglen {\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-3771-\tstruct ip_vs_service_entry\tfield_IP_VS_SO_GET_SERVICE;\nnet/netfilter/ipvs/ip_vs_ctl.c:3772:\tstruct ip_vs_get_dests\t\tfield_IP_VS_SO_GET_DESTS;\nnet/netfilter/ipvs/ip_vs_ctl.c-3773-\tstruct ip_vs_timeout_user\tfield_IP_VS_SO_GET_TIMEOUT;\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=3780=do_ip_vs_get_ctl(struct sock sk, int cmd, void __user user, int len)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-3914-\t{\nnet/netfilter/ipvs/ip_vs_ctl.c:3915:\t\tstruct ip_vs_get_dests get;\nnet/netfilter/ipvs/ip_vs_ctl.c-3916-\t\tsize_t size;\nnet/netfilter/ipvs/ip_vs_ctl.c-3917-\nnet/netfilter/ipvs/ip_vs_ctl.c:3918:\t\tget = (struct ip_vs_get_dests )arg;\nnet/netfilter/ipvs/ip_vs_ctl.c-3919-\t\tsize = struct_size(get, entrytable, get-\u003enum_dests);\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=4294=static struct ip_vs_service ip_vs_genl_find_service(struct netns_ipvs ipvs,\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-4304-\nnet/netfilter/ipvs/ip_vs_ctl.c:4305:static int ip_vs_genl_fill_dest(struct sk_buff skb, struct ip_vs_dest dest)\nnet/netfilter/ipvs/ip_vs_ctl.c-4306-{\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=4354=static int ip_vs_genl_dump_dest(struct sk_buff skb, struct ip_vs_dest *dest,\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-4364-\nnet/netfilter/ipvs/ip_vs_ctl.c:4365:\tif (ip_vs_genl_fill_dest(skb, dest) \u003c 0)\nnet/netfilter/ipvs/ip_vs_ctl.c-4366-\t\tgoto nla_put_failure;\n" }
25/3	2026/09/07 22:12	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 13628 output: 44 thoughts: 39 Thoughts: Here's a summary of my thought process: Diving into the IPVS Control Plane Okay, time to get my hands dirty and understand how these IPVS destinations are handled at the control plane level. I'm going to jump into the `ip_vs_ctl.c` file and specifically focus on the functions `ip_vs_genl_fill_dest` and `__ip_vs_get_dest_entries`. These names are pretty descriptive, so I'm expecting `ip_vs_genl_fill_dest` to be responsible for populating the destination information, probably using Generic Netlink, and `__ip_vs_get_dest_entries` should be the lower-level function that actually retrieves this destination data. I'm interested in how these work together to provide the necessary information for the user space control utility to manage the load balancing destinations. Let's see how they interact and what's going on under the hood. I want to see if there are any subtle optimization techniques, or possible areas of improvement here. This should provide some solid insight into how IPVS configures and stores destination entries.
26/3	2026/09/07 22:12	tool	read-file	0m Args: { "File": "net/netfilter/ipvs/ip_vs_ctl.c", "FirstLine": 3690, "LineCount": 40 } Results: { "Contents": "3690:\t\t\tsvc = __ip_vs_svc_fwm_find(ipvs, AF_INET, get-\u003efwmark);\n3691:\t\telse\n3692:\t\t\tsvc = __ip_vs_service_find(ipvs, AF_INET, get-\u003eprotocol, \u0026addr,\n3693:\t\t\t\t\t\t get-\u003eport);\n3694:\t\trcu_read_unlock();\n3695:\t\n3696:\t\tif (svc) {\n3697:\t\t\tint count = 0;\n3698:\t\t\tstruct ip_vs_dest dest;\n3699:\t\t\tstruct ip_vs_dest_entry entry;\n3700:\t\t\tstruct ip_vs_kstats kstats;\n3701:\t\n3702:\t\t\tmemset(\u0026entry, 0, sizeof(entry));\n3703:\t\t\tlist_for_each_entry(dest, \u0026svc-\u003edestinations, n_list) {\n3704:\t\t\t\tif (count \u003e= get-\u003enum_dests)\n3705:\t\t\t\t\tbreak;\n3706:\t\n3707:\t\t\t\t/ Cannot expose heterogeneous members via sockopt\n3708:\t\t\t\t * interface\n3709:\t\t\t\t */\n3710:\t\t\t\tif (dest-\u003eaf != svc-\u003eaf)\n3711:\t\t\t\t\tcontinue;\n3712:\t\n3713:\t\t\t\tentry.addr = dest-\u003eaddr.ip;\n3714:\t\t\t\tentry.port = dest-\u003eport;\n3715:\t\t\t\tentry.conn_flags = atomic_read(\u0026dest-\u003econn_flags);\n3716:\t\t\t\tentry.weight = atomic_read(\u0026dest-\u003eweight);\n3717:\t\t\t\tentry.u_threshold = READ_ONCE(dest-\u003eu_threshold);\n3718:\t\t\t\tentry.l_threshold = READ_ONCE(dest-\u003el_threshold);\n3719:\t\t\t\tentry.activeconns = atomic_read(\u0026dest-\u003eactiveconns);\n3720:\t\t\t\tentry.inactconns = ip_vs_dest_inactconns(dest);\n3721:\t\t\t\tentry.persistconns = atomic_read(\u0026dest-\u003epersistconns);\n3722:\t\t\t\tip_vs_copy_stats(\u0026kstats, \u0026dest-\u003estats);\n3723:\t\t\t\tip_vs_export_stats_user(\u0026entry.stats, \u0026kstats);\n3724:\t\t\t\tif (copy_to_user(\u0026uptr-\u003eentrytable[count],\n3725:\t\t\t\t\t\t \u0026entry, sizeof(entry))) {\n3726:\t\t\t\t\tret = -EFAULT;\n3727:\t\t\t\t\tbreak;\n3728:\t\t\t\t}\n3729:\t\t\t\tcount++;\n" }
27/3	2026/09/07 22:12	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 14618 output: 44 thoughts: 17 Thoughts: Okay, here's my attempt at summarizing that thought process, tailored for an expert audience: Diving into `ip_vs_genl_fill_dest` Right, let's circle back and take a look at `ip_vs_genl_fill_dest`. I need to ensure that the destination filling logic within the generic netlink interface is functioning as expected. It's a critical piece for proper forwarding within the IPVS setup, so a comprehensive review is in order. Specifically, I'll be looking for potential issues related to data integrity, performance bottlenecks, or any unexpected side effects. Making sure this function is solid is key for overall stability and efficient load balancing.
28/3	2026/09/07 22:12	tool	read-file	0m Args: { "File": "net/netfilter/ipvs/ip_vs_ctl.c", "FirstLine": 4305, "LineCount": 45 } Results: { "Contents": "4305:\tstatic int ip_vs_genl_fill_dest(struct sk_buff skb, struct ip_vs_dest dest)\n4306:\t{\n4307:\t\tstruct nlattr *nl_dest;\n4308:\t\tstruct ip_vs_kstats kstats;\n4309:\t\n4310:\t\tnl_dest = nla_nest_start_noflag(skb, IPVS_CMD_ATTR_DEST);\n4311:\t\tif (!nl_dest)\n4312:\t\t\treturn -EMSGSIZE;\n4313:\t\n4314:\t\tif (nla_put(skb, IPVS_DEST_ATTR_ADDR, sizeof(dest-\u003eaddr), \u0026dest-\u003eaddr) \|\|\n4315:\t\t nla_put_be16(skb, IPVS_DEST_ATTR_PORT, dest-\u003eport) \|\|\n4316:\t\t nla_put_u32(skb, IPVS_DEST_ATTR_FWD_METHOD,\n4317:\t\t\t\t(atomic_read(\u0026dest-\u003econn_flags) \u0026\n4318:\t\t\t\t IP_VS_CONN_F_FWD_MASK)) \|\|\n4319:\t\t nla_put_u32(skb, IPVS_DEST_ATTR_WEIGHT,\n4320:\t\t\t\tatomic_read(\u0026dest-\u003eweight)) \|\|\n4321:\t\t nla_put_u8(skb, IPVS_DEST_ATTR_TUN_TYPE,\n4322:\t\t\t dest-\u003etun_type) \|\|\n4323:\t\t nla_put_be16(skb, IPVS_DEST_ATTR_TUN_PORT,\n4324:\t\t\t\t dest-\u003etun_port) \|\|\n4325:\t\t nla_put_u16(skb, IPVS_DEST_ATTR_TUN_FLAGS,\n4326:\t\t\t\tdest-\u003etun_flags) \|\|\n4327:\t\t nla_put_u32(skb, IPVS_DEST_ATTR_U_THRESH,\n4328:\t\t\t\tREAD_ONCE(dest-\u003eu_threshold)) \|\|\n4329:\t\t nla_put_u32(skb, IPVS_DEST_ATTR_L_THRESH,\n4330:\t\t\t\tREAD_ONCE(dest-\u003el_threshold)) \|\|\n4331:\t\t nla_put_u32(skb, IPVS_DEST_ATTR_ACTIVE_CONNS,\n4332:\t\t\t\tatomic_read(\u0026dest-\u003eactiveconns)) \|\|\n4333:\t\t nla_put_u32(skb, IPVS_DEST_ATTR_INACT_CONNS,\n4334:\t\t\t\tip_vs_dest_inactconns(dest)) \|\|\n4335:\t\t nla_put_u32(skb, IPVS_DEST_ATTR_PERSIST_CONNS,\n4336:\t\t\t\tatomic_read(\u0026dest-\u003epersistconns)) \|\|\n4337:\t\t nla_put_u16(skb, IPVS_DEST_ATTR_ADDR_FAMILY, dest-\u003eaf))\n4338:\t\t\tgoto nla_put_failure;\n4339:\t\tip_vs_copy_stats(\u0026kstats, \u0026dest-\u003estats);\n4340:\t\tif (ip_vs_genl_fill_stats(skb, IPVS_DEST_ATTR_STATS, \u0026kstats))\n4341:\t\t\tgoto nla_put_failure;\n4342:\t\tif (ip_vs_genl_fill_stats64(skb, IPVS_DEST_ATTR_STATS64, \u0026kstats))\n4343:\t\t\tgoto nla_put_failure;\n4344:\t\n4345:\t\tnla_nest_end(skb, nl_dest);\n4346:\t\n4347:\t\treturn 0;\n4348:\t\n4349:\tnla_put_failure:\n" }
29/3	2026/09/07 22:12	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 15813 output: 40 thoughts: 627 Thoughts: Analyzing the IPVS Destination Overload Tracking Patch Okay, let's dive into this patch. My initial thought is to understand exactly what's changing. It looks like it's an optimization and refactoring of how IPVS tracks destination overload. Previously, the `IP_VS_DEST_F_OVERLOAD` flag in `dest->flags` was the go-to indicator. The patch removes this flag, and is going to utilize `dest->l_threshold_val` directly. Clever, using a non-zero value for `l_threshold_val` as the overload indicator, which seems like a good choice to optimize the cache lines. I immediately want to verify the implications of this change. Since `dest` is allocated using `kzalloc_obj`, which calls `kzalloc`, I need to confirm that this doesn't introduce any uninitialized fields or potential information leaks. Given my experience, I’m thinking there is a chance there are side effects. I recall `kzalloc` zero-initializes the allocated memory. I need to make sure this is true for `struct ip_vs_dest`. So, the next step is to make sure `struct ip_vs_dest` is never copied directly to userspace. Good, from my understanding of the relevant code, `__ip_vs_get_dest_entries` and generic netlink, only individual fields are copied, and those fields are explicitly initialized. That's a huge relief. No new kernel structures are being exposed, and no uninitialized memory is read or branched upon. The patch's choice to zero-initialize the memory allocation for `dest` is sound and it's also good that everything is explicitly set or updated after allocation. Now, let's consider the scheduler interactions. I see that the code simply replaces `(dest->flags & IP_VS_DEST_F_OVERLOAD)` checks with `ip_vs_dest_is_overloaded(dest)`. That should be a straightforward substitution as long as the semantics are identical. I want to double-check that the `ip_vs_dest_is_overloaded` function correctly reflects the overload state based on the new `l_threshold_val` approach. It's using `<=` and `>=` with `l_threshold_val` and `u_threshold_val` in `ip_vs_conn.c`, which makes sense. Finally, I need to perform a comprehensive sweep to confirm that this change is contained. I'll search the code for any uses of `l_threshold_val` or `u_threshold_val` to make sure there are no other places where this could cause uninitialized memory reads or introduce unexpected behavior. I'll need to do a full grep to make sure I don't miss anything.
30/3	2026/09/07 22:12	tool	grepper	0m Args: { "Expression": "(l_threshold_val\|u_threshold_val)", "PathPrefix": "net/netfilter/ipvs" } Results: { "Output": "net/netfilter/ipvs/ip_vs_conn.c=1089=ip_vs_bind_dest(struct ip_vs_conn cp, struct ip_vs_dest dest)\n--\nnet/netfilter/ipvs/ip_vs_conn.c-1152-\t\ttc = atomic_inc_return(\u0026dest-\u003etotalconns);\nnet/netfilter/ipvs/ip_vs_conn.c:1153:\t\tif (tc \u003e= READ_ONCE(dest-\u003eu_threshold_val))\nnet/netfilter/ipvs/ip_vs_conn.c-1154-\t\t\tip_vs_dest_update_overload(dest, true);\n--\nnet/netfilter/ipvs/ip_vs_conn.c=1220=static inline void ip_vs_unbind_dest(struct ip_vs_conn cp)\n--\nnet/netfilter/ipvs/ip_vs_conn.c-1245-\t\ttc = atomic_fetch_dec(\u0026dest-\u003etotalconns);\nnet/netfilter/ipvs/ip_vs_conn.c:1246:\t\tif (tc \u003c= READ_ONCE(dest-\u003el_threshold_val))\nnet/netfilter/ipvs/ip_vs_conn.c-1247-\t\t\tip_vs_dest_update_overload(dest, false);\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=1312=static void __ip_vs_dest_update_overload(struct ip_vs_dest dest, bool overload)\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-1323-\t\tif (conns \u003e= (overload ? l : u)) {\nnet/netfilter/ipvs/ip_vs_ctl.c:1324:\t\t\tWRITE_ONCE(dest-\u003eu_threshold_val, INT_MAX);\nnet/netfilter/ipvs/ip_vs_ctl.c:1325:\t\t\tWRITE_ONCE(dest-\u003el_threshold_val, l);\nnet/netfilter/ipvs/ip_vs_ctl.c-1326-\t\t\treturn;\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-1329-\nnet/netfilter/ipvs/ip_vs_ctl.c:1330:\tWRITE_ONCE(dest-\u003eu_threshold_val, u ? : INT_MAX);\nnet/netfilter/ipvs/ip_vs_ctl.c:1331:\tWRITE_ONCE(dest-\u003el_threshold_val, 0);\nnet/netfilter/ipvs/ip_vs_ctl.c-1332-}\n" }
31/3	2026/09/07 22:12	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 17728 output: 35 thoughts: 43 Thoughts: Okay, let's see, I need to get a clear picture of this code change. First, I need to look at the `flags` field within the `ip_vs_dest` structure. Specifically, I need to understand what's new about it with this patch. Was there anything set in `dest->flags` previously? I'm going to consult the definition of `IP_VS_DEST_F_` to confirm what was already there. This is all about ensuring I understand the potential impact of these flag changes on existing behavior and what might have been added. I need to be precise, or I'll introduce a subtle bug.
32/3	2026/09/07 22:12	tool	grepper	0m Error: no matches Args: { "Expression": "IP_VS_DEST_F_", "PathPrefix": "net/netfilter/ipvs" } Results: { "error": "no matches" }
33/3	2026/09/07 22:12	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 17958 output: 22 thoughts: 33 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Investigating `IP_VS_DEST_F_` Flag Usage Okay, so I've got this `IP_VS_DEST_F_` flag kicking around, and I need to understand its role and where it's actually used within the kernel's IPVS implementation. My first move is to dive straight into the source code. I'm going to start with the most likely place, which is the `include/net/ip_vs.h` header file. That's the logical starting point for defining and, hopefully, documenting what the flag even means. However, I'm not going to stop there. I know how easily things can be buried or defined in multiple places. So, after a quick peek in `ip_vs.h`, I'll use grep or a similar tool to scour the entire kernel tree. I'm looking for any instance of `IP_VS_DEST_F_`, to get the complete picture. I want to see how it's being set, checked, and modified. Context is key here; the header file likely only provides the static definition and maybe some basic documentation. The real meat of the story lies in the practical implementation. Let's see what the code has to say.
34/3	2026/09/07 22:12	tool	grepper	0m Error: no matches Args: { "Expression": "IP_VS_DEST_F_" } Results: { "error": "no matches" }
35/3	2026/09/07 22:12	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 18311 output: 229 thoughts: 249 Thoughts: My Assessment of the "IP_VS_DEST_F_OVERLOAD" Flag Okay, so it looks like `IP_VS_DEST_F_OVERLOAD` was indeed the only flag in question here. Let's run through the checklist to be absolutely sure. First, the possibility of kernel structures being sent directly to userspace with uninitialized fields. But, the code explicitly doesn't do that. The `struct ip_vs_dest` isn't directly exposed; getters copy selected, initialized fields into zeroed buffers. They use `memset(&entry, 0, ...)` and individual Netlink attributes, so that's covered. Next, conditional logic or branching that might rely on uninitialized variables. Hmm, looking at it, all fields of `dest` are allocated using `kzalloc_obj()`, which, as I recall, zeroes the allocated memory. They're also initialized within `ip_vs_new_dest` or `__ip_vs_update_dest`. That removes this concern too. Then there's the chance of allocations or complex data structure initialization where later code paths might access uninitialized data. However, there aren't any uninitialized fields. That's a good thing. Finally, bounds checks or logic that might allow surrounding code to access uninitialized bytes. This doesn't seem applicable here. Alright, after reviewing all the criteria, it's clear that this patch doesn't introduce any uninitialized memory risks. Dedicated KMSAN fuzzing isn't required. We can confidently move forward. I'll prepare the call to `set-results`.
36/3	2026/09/07 22:12	tool	set-results	0m Args: { "KMSANReasoning": "The patch reorganizes fields in `struct ip_vs_dest` for better cacheline utilization and refactors the destination overload status tracking to use `l_threshold_val` / `u_threshold_val` instead of `dest-\u003eflags` with `IP_VS_DEST_F_OVERLOAD`.\n\nAll `struct ip_vs_dest` instances are zero-allocated with `kzalloc_obj()` and their threshold fields are properly initialized upon creation. The structure itself is not copied to userspace as a raw blob; userspace queries serialize individual fields or use zeroed intermediate structures (`memset` in `__ip_vs_get_dest_entries` and individual Netlink attributes in `ip_vs_genl_fill_dest`). No uninitialized memory is read, copied to userspace, or branched upon.\n\nBecause the changes introduce no uninitialized memory risks, a dedicated KMSAN fuzzing session is not warranted. Standard KASAN fuzzing is sufficient.", "NeedsKMSAN": false } Results: { "KMSANReasoning": "The patch reorganizes fields in `struct ip_vs_dest` for better cacheline utilization and refactors the destination overload status tracking to use `l_threshold_val` / `u_threshold_val` instead of `dest-\u003eflags` with `IP_VS_DEST_F_OVERLOAD`.\n\nAll `struct ip_vs_dest` instances are zero-allocated with `kzalloc_obj()` and their threshold fields are properly initialized upon creation. The structure itself is not copied to userspace as a raw blob; userspace queries serialize individual fields or use zeroed intermediate structures (`memset` in `__ip_vs_get_dest_entries` and individual Netlink attributes in `ip_vs_genl_fill_dest`). No uninitialized memory is read, copied to userspace, or branched upon.\n\nBecause the changes introduce no uninitialized memory risks, a dedicated KMSAN fuzzing session is not warranted. Standard KASAN fuzzing is sufficient.", "NeedsKMSAN": false }

LLM Calls Summary:
Total Calls	Total Tokens	Avg Tokens	Total Duration (Seconds)	Avg Duration (Seconds)

Tool Calls Summary:
Total Calls	Total Duration (Seconds)	Avg Duration (Seconds)