AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/09/05 12:42	flow	patch-triage	0m Args: null Results: { "EnableConfigs": [ "PPP", "PPP_ASYNC", "PPP_SYNC_TTY", "PPPOE", "PPTP", "PPPOATM", "PPPOL2TP", "ATM", "L2TP", "NET_IPGRE_DEMUX" ], "FocusSymbols": [ "ppp_async_ioctl", "ppp_async_send", "ppp_sync_ioctl", "ppp_sync_send", "pppoe_xmit", "pppoe_fill_forward_path", "pptp_xmit", "pptp_ppp_ioctl", "pppoatm_send", "pppoatm_devppp_ioctl", "pppol2tp_xmit", "ppp_push", "ppp_mp_explode", "__ppp_channel_push", "ppp_channel_bridge_input", "ppp_ioctl", "ppp_fill_forward_path" ], "KMSANReasoning": "The patch is a signature refactoring across the PPP subsystem: `struct ppp_channel_ops` callbacks (`start_xmit`, `ioctl`, and `fill_forward_path`) are updated to accept the channel's `private` pointer directly instead of `struct ppp_channel *`. This change does not introduce or modify any memory allocations, buffer initializations, stack variables, or copy operations to userspace. No uninitialized memory paths or info-leak risks are created. Standard bug detectors and KASAN are sufficient to catch any pointer-related regressions.", "NeedsKMSAN": false, "Reasoning": "The patch refactors the ppp_channel_ops interface (start_xmit, ioctl, fill_forward_path) to pass the channel private pointer directly instead of struct ppp_channel. It updates the callers in ppp_generic as well as implementations across PPP channel modules (ppp_async, ppp_synctty, pppoe, pptp, pppoatm, pppol2tp). These networking drivers and protocols are reachable via sockets and /dev/ppp ioctls in standard virtualized environments and should be fuzzed to catch any regressions.", "WorthFuzzing": true }
1/1	2026/09/05 12:42	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit 2e25189b6b8060c044e56218c2a77a83e3f5f0b1\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Sat Sep 5 12:42:49 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c\nindex ea7fe9608ffd6..e73b0fce86b91 100644\n--- a/drivers/net/ppp/ppp_async.c\n+++ b/drivers/net/ppp/ppp_async.c\n@@ -91,13 +91,12 @@ MODULE_ALIAS_LDISC(N_PPP);\n * Prototypes.\n /\n static int ppp_async_encode(struct asyncppp ap);\n-static int ppp_async_send(struct ppp_channel chan, struct sk_buff skb);\n+static int ppp_async_send(void private, struct sk_buff skb);\n static int ppp_async_push(struct asyncppp ap);\n static void ppp_async_flush_output(struct asyncppp ap);\n static void ppp_async_input(struct asyncppp ap, const unsigned char buf,\n \t\t\t const u8 flags, int count);\n-static int ppp_async_ioctl(struct ppp_channel chan, unsigned int cmd,\n-\t\t\t unsigned long arg);\n+static int ppp_async_ioctl(void private, unsigned int cmd, unsigned long arg);\n static void ppp_async_process(struct tasklet_struct t);\n \n static void async_lcp_peek(struct asyncppp ap, unsigned char data,\n@@ -321,9 +320,9 @@ ppp_async_init(void)\n * The following routines provide the PPP channel interface.\n /\n static int\n-ppp_async_ioctl(struct ppp_channel chan, unsigned int cmd, unsigned long arg)\n+ppp_async_ioctl(void private, unsigned int cmd, unsigned long arg)\n {\n-\tstruct asyncppp ap = chan-\u003eprivate;\n+\tstruct asyncppp ap = private;\n \tvoid __user argp = (void __user )arg;\n \tint __user p = argp;\n \tint err, val;\n@@ -550,9 +549,9 @@ ppp_async_encode(struct asyncppp ap)\n at some later time.\n /\n static int\n-ppp_async_send(struct ppp_channel chan, struct sk_buff skb)\n+ppp_async_send(void private, struct sk_buff skb)\n {\n-\tstruct asyncppp ap = chan-\u003eprivate;\n+\tstruct asyncppp ap = private;\n \n \tppp_async_push(ap);\n \ndiff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c\nindex 1a610a18893ba..3b83ff8cf5895 100644\n--- a/drivers/net/ppp/ppp_generic.c\n+++ b/drivers/net/ppp/ppp_generic.c\n@@ -790,7 +790,7 @@ static long ppp_ioctl(struct file file, unsigned int cmd, unsigned long arg)\n \t\t\tchan = pch-\u003echan;\n \t\t\terr = -ENOTTY;\n \t\t\tif (chan \u0026\u0026 chan-\u003eops-\u003eioctl)\n-\t\t\t\terr = chan-\u003eops-\u003eioctl(chan, cmd, arg);\n+\t\t\t\terr = chan-\u003eops-\u003eioctl(chan-\u003eprivate, cmd, arg);\n \t\t\tmutex_unlock(\u0026pch-\u003echan_sem);\n \t\t}\n \t\tgoto out;\n@@ -1603,7 +1603,7 @@ static int ppp_fill_forward_path(struct net_device_path_ctx ctx,\n \tif (!chan-\u003eops-\u003efill_forward_path)\n \t\treturn -EOPNOTSUPP;\n \n-\treturn chan-\u003eops-\u003efill_forward_path(ctx, path, chan);\n+\treturn chan-\u003eops-\u003efill_forward_path(ctx, path, chan-\u003eprivate);\n }\n \n static const struct net_device_ops ppp_netdev_ops = {\n@@ -1932,7 +1932,7 @@ ppp_push(struct ppp ppp, struct sk_buff skb)\n \t\t\tgoto out;\n \t\t}\n \n-\t\tret = chan-\u003eops-\u003estart_xmit(chan, skb);\n+\t\tret = chan-\u003eops-\u003estart_xmit(chan-\u003eprivate, skb);\n \n out:\n \t\tspin_unlock(\u0026pch-\u003edownl);\n@@ -2142,7 +2142,7 @@ static int ppp_mp_explode(struct ppp ppp, struct sk_buff skb)\n \t\t/ try to send it down the channel /\n \t\tchan = pch-\u003echan;\n \t\tif (!skb_queue_empty(\u0026pch-\u003efile.xq) \|\|\n-\t\t\t!chan-\u003eops-\u003estart_xmit(chan, frag))\n+\t\t\t!chan-\u003eops-\u003estart_xmit(chan-\u003eprivate, frag))\n \t\t\tskb_queue_tail(\u0026pch-\u003efile.xq, frag);\n \t\tpch-\u003ehad_frag = 1;\n \t\tp += flen;\n@@ -2175,7 +2175,7 @@ static void __ppp_channel_push(struct channel pch, struct ppp ppp)\n \tif (pch-\u003echan) {\n \t\twhile (!skb_queue_empty(\u0026pch-\u003efile.xq)) {\n \t\t\tskb = skb_dequeue(\u0026pch-\u003efile.xq);\n-\t\t\tif (!pch-\u003echan-\u003eops-\u003estart_xmit(pch-\u003echan, skb)) {\n+\t\t\tif (!pch-\u003echan-\u003eops-\u003estart_xmit(pch-\u003echan-\u003eprivate, skb)) {\n \t\t\t\t/ put the packet back and try again later /\n \t\t\t\tskb_queue_head(\u0026pch-\u003efile.xq, skb);\n \t\t\t\tbreak;\n@@ -2300,7 +2300,7 @@ static bool ppp_channel_bridge_input(struct channel pch, struct sk_buff skb)\n \t}\n \n \tskb_scrub_packet(skb, !net_eq(pch-\u003echan_net, pchb-\u003echan_net));\n-\tif (!pchb-\u003echan-\u003eops-\u003estart_xmit(pchb-\u003echan, skb))\n+\tif (!pchb-\u003echan-\u003eops-\u003estart_xmit(pchb-\u003echan-\u003eprivate, skb))\n \t\tkfree_skb(skb);\n \n outl:\ndiff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c\nindex f87d43faeeab5..54d8402e18c4a 100644\n--- a/drivers/net/ppp/ppp_synctty.c\n+++ b/drivers/net/ppp/ppp_synctty.c\n@@ -81,9 +81,8 @@ struct syncppp {\n Prototypes.\n /\n static struct sk_buff ppp_sync_txmunge(struct syncppp ap, struct sk_buff );\n-static int ppp_sync_send(struct ppp_channel chan, struct sk_buff skb);\n-static int ppp_sync_ioctl(struct ppp_channel chan, unsigned int cmd,\n-\t\t\t unsigned long arg);\n+static int ppp_sync_send(void private, struct sk_buff skb);\n+static int ppp_sync_ioctl(void private, unsigned int cmd, unsigned long arg);\n static void ppp_sync_process(struct tasklet_struct t);\n static int ppp_sync_push(struct syncppp ap);\n static void ppp_sync_flush_output(struct syncppp ap);\n@@ -312,9 +311,9 @@ ppp_sync_init(void)\n The following routines provide the PPP channel interface.\n /\n static int\n-ppp_sync_ioctl(struct ppp_channel chan, unsigned int cmd, unsigned long arg)\n+ppp_sync_ioctl(void private, unsigned int cmd, unsigned long arg)\n {\n-\tstruct syncppp ap = chan-\u003eprivate;\n+\tstruct syncppp ap = private;\n \tint err, val;\n \tu32 accm[8];\n \tvoid __user argp = (void __user )arg;\n@@ -491,9 +490,9 @@ ppp_sync_txmunge(struct syncppp ap, struct sk_buff skb)\n at some later time.\n /\n static int\n-ppp_sync_send(struct ppp_channel chan, struct sk_buff skb)\n+ppp_sync_send(void private, struct sk_buff skb)\n {\n-\tstruct syncppp ap = chan-\u003eprivate;\n+\tstruct syncppp ap = private;\n \n \tppp_sync_push(ap);\n \ndiff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c\nindex bf7414b46a260..7584535035257 100644\n--- a/drivers/net/ppp/pppoe.c\n+++ b/drivers/net/ppp/pppoe.c\n@@ -841,9 +841,9 @@ static int pppoe_sendmsg(struct socket sock, struct msghdr m,\n sends PPP frame over PPPoE socket\n \n *********************************************************************/\n-static int pppoe_xmit(struct ppp_channel chan, struct sk_buff skb)\n+static int pppoe_xmit(void private, struct sk_buff skb)\n {\n-\tstruct sock sk = chan-\u003eprivate;\n+\tstruct sock sk = private;\n \tstruct pppox_sock po = pppox_sk(sk);\n \tstruct net_device dev = po-\u003epppoe_dev;\n \tstruct pppoe_hdr ph;\n@@ -895,9 +895,9 @@ static int pppoe_xmit(struct ppp_channel chan, struct sk_buff skb)\n \n static int pppoe_fill_forward_path(struct net_device_path_ctx ctx,\n \t\t\t\t struct net_device_path path,\n-\t\t\t\t const struct ppp_channel chan)\n+\t\t\t\t void private)\n {\n-\tstruct sock sk = chan-\u003eprivate;\n+\tstruct sock sk = private;\n \tstruct pppox_sock po = pppox_sk(sk);\n \tstruct net_device dev = po-\u003epppoe_dev;\n \ndiff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c\nindex a797a0606f6b4..8f7190d7067e9 100644\n--- a/drivers/net/ppp/pptp.c\n+++ b/drivers/net/ppp/pptp.c\n@@ -146,9 +146,9 @@ static struct rtable pptp_route_output(const struct pppox_sock po,\n \treturn ip_route_output_flow(net, fl4, sk);\n }\n \n-static int pptp_xmit(struct ppp_channel chan, struct sk_buff skb)\n+static int pptp_xmit(void private, struct sk_buff skb)\n {\n-\tstruct sock sk = chan-\u003eprivate;\n+\tstruct sock sk = private;\n \tstruct pppox_sock po = pppox_sk(sk);\n \tstruct net net = sock_net(sk);\n \tstruct pptp_opt opt = \u0026po-\u003eproto.pptp;\n@@ -573,10 +573,9 @@ static int pptp_create(struct net net, struct socket sock, int kern)\n \treturn error;\n }\n \n-static int pptp_ppp_ioctl(struct ppp_channel chan, unsigned int cmd,\n-\tunsigned long arg)\n+static int pptp_ppp_ioctl(void private, unsigned int cmd, unsigned long arg)\n {\n-\tstruct sock sk = chan-\u003eprivate;\n+\tstruct sock sk = private;\n \tstruct pppox_sock po = pppox_sk(sk);\n \tstruct pptp_opt opt = \u0026po-\u003eproto.pptp;\n \tvoid __user argp = (void __user )arg;\ndiff --git a/include/linux/ppp_channel.h b/include/linux/ppp_channel.h\nindex 2f63e9a6cc889..d9cfb8ef0ffac 100644\n--- a/include/linux/ppp_channel.h\n+++ b/include/linux/ppp_channel.h\n@@ -27,12 +27,12 @@ struct ppp_channel;\n struct ppp_channel_ops {\n \t/ Send a packet (or multilink fragment) on this channel.\n \t Returns 1 if it was accepted, 0 if not. /\n-\tint\t(start_xmit)(struct ppp_channel , struct sk_buff );\n+\tint\t(start_xmit)(void , struct sk_buff );\n \t/ Handle an ioctl call that has come in via /dev/ppp. /\n-\tint\t(ioctl)(struct ppp_channel , unsigned int, unsigned long);\n+\tint\t(ioctl)(void , unsigned int, unsigned long);\n \tint\t(fill_forward_path)(struct net_device_path_ctx ,\n \t\t\t\t struct net_device_path ,\n-\t\t\t\t const struct ppp_channel );\n+\t\t\t\t void );\n };\n \n struct ppp_channel {\ndiff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c\nindex 6da52d12df68e..913324f9685f6 100644\n--- a/net/atm/pppoatm.c\n+++ b/net/atm/pppoatm.c\n@@ -91,11 +91,6 @@ static inline struct pppoatm_vcc atmvcc_to_pvcc(const struct atm_vcc atmvcc)\n \treturn (struct pppoatm_vcc ) (atmvcc-\u003euser_back);\n }\n \n-static inline struct pppoatm_vcc chan_to_pvcc(const struct ppp_channel chan)\n-{\n-\treturn (struct pppoatm_vcc ) (chan-\u003eprivate);\n-}\n-\n /\n We can't do this directly from our _pop handler, since the ppp code\n * doesn't want to be called in interrupt context, so we do it from\n@@ -286,9 +281,9 @@ static int pppoatm_may_send(struct pppoatm_vcc pvcc, int size)\n as success, just to be clear what we're really doing.\n /\n #define DROP_PACKET 1\n-static int pppoatm_send(struct ppp_channel chan, struct sk_buff skb)\n+static int pppoatm_send(void private, struct sk_buff skb)\n {\n-\tstruct pppoatm_vcc pvcc = chan_to_pvcc(chan);\n+\tstruct pppoatm_vcc pvcc = private;\n \tstruct atm_vcc vcc;\n \tint ret;\n \n@@ -366,16 +361,16 @@ static int pppoatm_send(struct ppp_channel chan, struct sk_buff skb)\n }\n \n /* This handles ioctls sent to the /dev/ppp interface /\n-static int pppoatm_devppp_ioctl(struct ppp_channel chan, unsigned int cmd,\n-\tunsigned long arg)\n+static int pppoatm_devppp_ioctl(void private, unsigned int cmd,\n+\t\t\t\tunsigned long arg)\n {\n+\tstruct pppoatm_vcc pvcc = private;\n+\n \tswitch (cmd) {\n \tcase PPPIOCGFLAGS:\n-\t\treturn put_user(chan_to_pvcc(chan)-\u003eflags, (int __user ) arg)\n-\t\t ? -EFAULT : 0;\n+\t\treturn put_user(pvcc-\u003eflags, (int __user )arg) ? -EFAULT : 0;\n \tcase PPPIOCSFLAGS:\n-\t\treturn get_user(chan_to_pvcc(chan)-\u003eflags, (int __user ) arg)\n-\t\t ? -EFAULT : 0;\n+\t\treturn get_user(pvcc-\u003eflags, (int __user )arg) ? -EFAULT : 0;\n \t}\n \treturn -ENOTTY;\n }\ndiff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c\nindex ef8fdfaf051d4..c1cda1d7fbf6b 100644\n--- a/net/l2tp/l2tp_ppp.c\n+++ b/net/l2tp/l2tp_ppp.c\n@@ -122,7 +122,7 @@ struct pppol2tp_session {\n \tstruct sock\t\t__sk;\t\t/ Copy of .sk, for cleanup /\n };\n \n-static int pppol2tp_xmit(struct ppp_channel chan, struct sk_buff skb);\n+static int pppol2tp_xmit(void private, struct sk_buff skb);\n \n static const struct ppp_channel_ops pppol2tp_chan_ops = {\n \t.start_xmit = pppol2tp_xmit,\n@@ -327,9 +327,9 @@ static int pppol2tp_sendmsg(struct socket sock, struct msghdr m,\n the skb it supplied, not our cloned skb. So we take care to always\n * leave the original skb unfreed if we return an error.\n /\n-static int pppol2tp_xmit(struct ppp_channel chan, struct sk_buff skb)\n+static int pppol2tp_xmit(void private, struct sk_buff skb)\n {\n-\tstruct sock sk = (struct sock )chan-\u003eprivate;\n+\tstruct sock sk = private;\n \tstruct l2tp_session session;\n \tstruct l2tp_tunnel tunnel;\n \tint uhlen, headroom;\n" }
2/1	2026/09/05 12:42	agent	patch-evaluator	0m Model: core Args: null Results: { "EnableConfigs": [ "PPP", "PPP_ASYNC", "PPP_SYNC_TTY", "PPPOE", "PPTP", "PPPOATM", "PPPOL2TP", "ATM", "L2TP", "NET_IPGRE_DEMUX" ], "FocusSymbols": [ "ppp_async_ioctl", "ppp_async_send", "ppp_sync_ioctl", "ppp_sync_send", "pppoe_xmit", "pppoe_fill_forward_path", "pptp_xmit", "pptp_ppp_ioctl", "pppoatm_send", "pppoatm_devppp_ioctl", "pppol2tp_xmit", "ppp_push", "ppp_mp_explode", "__ppp_channel_push", "ppp_channel_bridge_input", "ppp_ioctl", "ppp_fill_forward_path" ], "Reasoning": "The patch refactors the ppp_channel_ops interface (start_xmit, ioctl, fill_forward_path) to pass the channel private pointer directly instead of struct ppp_channel. It updates the callers in ppp_generic as well as implementations across PPP channel modules (ppp_async, ppp_synctty, pppoe, pptp, pppoatm, pppol2tp). These networking drivers and protocols are reachable via sockets and /dev/ppp ioctls in standard virtualized environments and should be fuzzed to catch any regressions.", "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 2e25189b6b8060c044e56218c2a77a83e3f5f0b1 Author: syz-cluster <triage@syzkaller.com> Date: Sat Sep 5 12:42:49 2026 +0000 syz-cluster: applied patch under review diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c index ea7fe9608ffd6..e73b0fce86b91 100644 --- a/drivers/net/ppp/ppp_async.c +++ b/drivers/net/ppp/ppp_async.c @@ -91,13 +91,12 @@ MODULE_ALIAS_LDISC(N_PPP); * Prototypes. / static int ppp_async_encode(struct asyncppp ap); -static int ppp_async_send(struct ppp_channel chan, struct sk_buff skb); +static int ppp_async_send(void private, struct sk_buff skb); static int ppp_async_push(struct asyncppp ap); static void ppp_async_flush_output(struct asyncppp ap); static void ppp_async_input(struct asyncppp ap, const unsigned char buf, const u8 flags, int count); -static int ppp_async_ioctl(struct ppp_channel chan, unsigned int cmd, - unsigned long arg); +static int ppp_async_ioctl(void private, unsigned int cmd, unsigned long arg); static void ppp_async_process(struct tasklet_struct t); static void async_lcp_peek(struct asyncppp ap, unsigned char data, @@ -321,9 +320,9 @@ ppp_async_init(void) * The following routines provide the PPP channel interface. / static int -ppp_async_ioctl(struct ppp_channel chan, unsigned int cmd, unsigned long arg) +ppp_async_ioctl(void private, unsigned int cmd, unsigned long arg) { - struct asyncppp ap = chan->private; + struct asyncppp ap = private; void __user argp = (void __user )arg; int __user p = argp; int err, val; @@ -550,9 +549,9 @@ ppp_async_encode(struct asyncppp ap) at some later time. / static int -ppp_async_send(struct ppp_channel chan, struct sk_buff skb) +ppp_async_send(void private, struct sk_buff skb) { - struct asyncppp ap = chan->private; + struct asyncppp ap = private; ppp_async_push(ap); diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c index 1a610a18893ba..3b83ff8cf5895 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -790,7 +790,7 @@ static long ppp_ioctl(struct file file, unsigned int cmd, unsigned long arg) chan = pch->chan; err = -ENOTTY; if (chan && chan->ops->ioctl) - err = chan->ops->ioctl(chan, cmd, arg); + err = chan->ops->ioctl(chan->private, cmd, arg); mutex_unlock(&pch->chan_sem); } goto out; @@ -1603,7 +1603,7 @@ static int ppp_fill_forward_path(struct net_device_path_ctx ctx, if (!chan->ops->fill_forward_path) return -EOPNOTSUPP; - return chan->ops->fill_forward_path(ctx, path, chan); + return chan->ops->fill_forward_path(ctx, path, chan->private); } static const struct net_device_ops ppp_netdev_ops = { @@ -1932,7 +1932,7 @@ ppp_push(struct ppp ppp, struct sk_buff skb) goto out; } - ret = chan->ops->start_xmit(chan, skb); + ret = chan->ops->start_xmit(chan->private, skb); out: spin_unlock(&pch->downl); @@ -2142,7 +2142,7 @@ static int ppp_mp_explode(struct ppp ppp, struct sk_buff skb) / try to send it down the channel / chan = pch->chan; if (!skb_queue_empty(&pch->file.xq) \|\| - !chan->ops->start_xmit(chan, frag)) + !chan->ops->start_xmit(chan->private, frag)) skb_queue_tail(&pch->file.xq, frag); pch->had_frag = 1; p += flen; @@ -2175,7 +2175,7 @@ static void __ppp_channel_push(struct channel pch, struct ppp ppp) if (pch->chan) { while (!skb_queue_empty(&pch->file.xq)) { skb = skb_dequeue(&pch->file.xq); - if (!pch->chan->ops->start_xmit(pch->chan, skb)) { + if (!pch->chan->ops->start_xmit(pch->chan->private, skb)) { / put the packet back and try again later / skb_queue_head(&pch->file.xq, skb); break; @@ -2300,7 +2300,7 @@ static bool ppp_channel_bridge_input(struct channel pch, struct sk_buff skb) } skb_scrub_packet(skb, !net_eq(pch->chan_net, pchb->chan_net)); - if (!pchb->chan->ops->start_xmit(pchb->chan, skb)) + if (!pchb->chan->ops->start_xmit(pchb->chan->private, skb)) kfree_skb(skb); outl: diff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c index f87d43faeeab5..54d8402e18c4a 100644 --- a/drivers/net/ppp/ppp_synctty.c +++ b/drivers/net/ppp/ppp_synctty.c @@ -81,9 +81,8 @@ struct syncppp { Prototypes. / static struct sk_buff ppp_sync_txmunge(struct syncppp ap, struct sk_buff ); -static int ppp_sync_send(struct ppp_channel chan, struct sk_buff skb); -static int ppp_sync_ioctl(struct ppp_channel chan, unsigned int cmd, - unsigned long arg); +static int ppp_sync_send(void private, struct sk_buff skb); +static int ppp_sync_ioctl(void private, unsigned int cmd, unsigned long arg); static void ppp_sync_process(struct tasklet_struct t); static int ppp_sync_push(struct syncppp ap); static void ppp_sync_flush_output(struct syncppp ap); @@ -312,9 +311,9 @@ ppp_sync_init(void) The following routines provide the PPP channel interface. / static int -ppp_sync_ioctl(struct ppp_channel chan, unsigned int cmd, unsigned long arg) +ppp_sync_ioctl(void private, unsigned int cmd, unsigned long arg) { - struct syncppp ap = chan->private; + struct syncppp ap = private; int err, val; u32 accm[8]; void __user argp = (void __user )arg; @@ -491,9 +490,9 @@ ppp_sync_txmunge(struct syncppp ap, struct sk_buff skb) at some later time. / static int -ppp_sync_send(struct ppp_channel chan, struct sk_buff skb) +ppp_sync_send(void private, struct sk_buff skb) { - struct syncppp ap = chan->private; + struct syncppp ap = private; ppp_sync_push(ap); diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c index bf7414b46a260..7584535035257 100644 --- a/drivers/net/ppp/pppoe.c +++ b/drivers/net/ppp/pppoe.c @@ -841,9 +841,9 @@ static int pppoe_sendmsg(struct socket sock, struct msghdr m, sends PPP frame over PPPoE socket * **********************************************************************/ -static int pppoe_xmit(struct ppp_channel chan, struct sk_buff skb) +static int pppoe_xmit(void private, struct sk_buff skb) { - struct sock sk = chan->private; + struct sock sk = private; struct pppox_sock po = pppox_sk(sk); struct net_device dev = po->pppoe_dev; struct pppoe_hdr ph; @@ -895,9 +895,9 @@ static int pppoe_xmit(struct ppp_channel chan, struct sk_buff skb) static int pppoe_fill_forward_path(struct net_device_path_ctx ctx, struct net_device_path path, - const struct ppp_channel chan) + void private) { - struct sock sk = chan->private; + struct sock sk = private; struct pppox_sock po = pppox_sk(sk); struct net_device dev = po->pppoe_dev; diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c index a797a0606f6b4..8f7190d7067e9 100644 --- a/drivers/net/ppp/pptp.c +++ b/drivers/net/ppp/pptp.c @@ -146,9 +146,9 @@ static struct rtable pptp_route_output(const struct pppox_sock po, return ip_route_output_flow(net, fl4, sk); } -static int pptp_xmit(struct ppp_channel chan, struct sk_buff skb) +static int pptp_xmit(void private, struct sk_buff skb) { - struct sock sk = chan->private; + struct sock sk = private; struct pppox_sock po = pppox_sk(sk); struct net net = sock_net(sk); struct pptp_opt opt = &po->proto.pptp; @@ -573,10 +573,9 @@ static int pptp_create(struct net net, struct socket sock, int kern) return error; } -static int pptp_ppp_ioctl(struct ppp_channel chan, unsigned int cmd, - unsigned long arg) +static int pptp_ppp_ioctl(void private, unsigned int cmd, unsigned long arg) { - struct sock sk = chan->private; + struct sock sk = private; struct pppox_sock po = pppox_sk(sk); struct pptp_opt opt = &po->proto.pptp; void __user argp = (void __user )arg; diff --git a/include/linux/ppp_channel.h b/include/linux/ppp_channel.h index 2f63e9a6cc889..d9cfb8ef0ffac 100644 --- a/include/linux/ppp_channel.h +++ b/include/linux/ppp_channel.h @@ -27,12 +27,12 @@ struct ppp_channel; struct ppp_channel_ops { / Send a packet (or multilink fragment) on this channel. Returns 1 if it was accepted, 0 if not. / - int (start_xmit)(struct ppp_channel , struct sk_buff ); + int (start_xmit)(void , struct sk_buff ); / Handle an ioctl call that has come in via /dev/ppp. / - int (ioctl)(struct ppp_channel , unsigned int, unsigned long); + int (ioctl)(void , unsigned int, unsigned long); int (fill_forward_path)(struct net_device_path_ctx , struct net_device_path , - const struct ppp_channel ); + void ); }; struct ppp_channel { diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c index 6da52d12df68e..913324f9685f6 100644 --- a/net/atm/pppoatm.c +++ b/net/atm/pppoatm.c @@ -91,11 +91,6 @@ static inline struct pppoatm_vcc atmvcc_to_pvcc(const struct atm_vcc atmvcc) return (struct pppoatm_vcc ) (atmvcc->user_back); } -static inline struct pppoatm_vcc chan_to_pvcc(const struct ppp_channel chan) -{ - return (struct pppoatm_vcc ) (chan->private); -} - /* * We can't do this directly from our _pop handler, since the ppp code * doesn't want to be called in interrupt context, so we do it from @@ -286,9 +281,9 @@ static int pppoatm_may_send(struct pppoatm_vcc pvcc, int size) as success, just to be clear what we're really doing. / #define DROP_PACKET 1 -static int pppoatm_send(struct ppp_channel chan, struct sk_buff skb) +static int pppoatm_send(void private, struct sk_buff skb) { - struct pppoatm_vcc pvcc = chan_to_pvcc(chan); + struct pppoatm_vcc pvcc = private; struct atm_vcc vcc; int ret; @@ -366,16 +361,16 @@ static int pppoatm_send(struct ppp_channel chan, struct sk_buff skb) } /* This handles ioctls sent to the /dev/ppp interface / -static int pppoatm_devppp_ioctl(struct ppp_channel chan, unsigned int cmd, - unsigned long arg) +static int pppoatm_devppp_ioctl(void private, unsigned int cmd, + unsigned long arg) { + struct pppoatm_vcc pvcc = private; + switch (cmd) { case PPPIOCGFLAGS: - return put_user(chan_to_pvcc(chan)->flags, (int __user ) arg) - ? -EFAULT : 0; + return put_user(pvcc->flags, (int __user )arg) ? -EFAULT : 0; case PPPIOCSFLAGS: - return get_user(chan_to_pvcc(chan)->flags, (int __user ) arg) - ? -EFAULT : 0; + return get_user(pvcc->flags, (int __user )arg) ? -EFAULT : 0; } return -ENOTTY; } diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index ef8fdfaf051d4..c1cda1d7fbf6b 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -122,7 +122,7 @@ struct pppol2tp_session { struct sock __sk; / Copy of .sk, for cleanup / }; -static int pppol2tp_xmit(struct ppp_channel chan, struct sk_buff skb); +static int pppol2tp_xmit(void private, struct sk_buff skb); static const struct ppp_channel_ops pppol2tp_chan_ops = { .start_xmit = pppol2tp_xmit, @@ -327,9 +327,9 @@ static int pppol2tp_sendmsg(struct socket sock, struct msghdr m, the skb it supplied, not our cloned skb. So we take care to always * leave the original skb unfreed if we return an error. / -static int pppol2tp_xmit(struct ppp_channel chan, struct sk_buff skb) +static int pppol2tp_xmit(void private, struct sk_buff skb) { - struct sock sk = (struct sock )chan->private; + struct sock sk = private; struct l2tp_session session; struct l2tp_tunnel tunnel; int uhlen, headroom;
3/2	2026/09/05 12:42	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 7201 output: 19 thoughts: 612 Thoughts: Analyzing the PPP Channel Operations Patch Okay, let's dive into this patch and figure out its fuzzing potential and how to best approach it. My initial thought is to assess if the modifications are significant enough to warrant fuzzing, and if so, what configurations and focus symbols would be most effective. The patch touches a bunch of `ppp` related files: `drivers/net/ppp/ppp_async.c`, `drivers/net/ppp/ppp_generic.c`, `drivers/net/ppp/ppp_synctty.c`, `drivers/net/ppp/pppoe.c`, `drivers/net/ppp/pptp.c`, `include/linux/ppp_channel.h`, `net/atm/pppoatm.c`, and `net/l2tp/l2tp_ppp.c`. So, it's definitely spreading across the PPP stack. Looking at the changes, it seems like the core of this patch revolves around altering the `struct ppp_channel_ops`. Specifically, the function signatures of `start_xmit`, `ioctl`, and `fill_forward_path` are being tweaked. They're changing from taking a `struct ppp_channel ` as the first argument, to taking a `void ` instead. This also means corresponding updates in the caller sites. It looks like they're now passing `chan->private` to these functions instead of `chan` itself in `ppp_generic.c`. Alright, so the implementations are also updated: `ppp_async_ioctl`, `ppp_async_send`, `ppp_sync_ioctl`, `ppp_sync_send`, `pppoe_xmit`, `pppoe_fill_forward_path`, `pptp_xmit`, `pptp_ppp_ioctl`, `pppoatm_send`, `pppoatm_devppp_ioctl` and `pppol2tp_xmit` are all being touched. Now, before I decide on a fuzzing strategy, I need to make sure this is a comprehensive change. I need to quickly scan the entire codebase to verify that no other implementations of `ppp_channel_ops` have been missed. Gotta use `grepper` and see what else pops up! I'm hoping this is a complete and clean refactor, but it's always worth a thorough check. Then it's time to compile it and confirm it all works as intended.
4/2	2026/09/05 12:42	tool	grepper	0m Args: { "Expression": "ppp_channel_ops" } Results: { "Output": "drivers/net/ppp/ppp_async.c=102=static void async_lcp_peek(struct asyncppp ap, unsigned char data,\n--\ndrivers/net/ppp/ppp_async.c-104-\ndrivers/net/ppp/ppp_async.c:105:static const struct ppp_channel_ops async_ops = {\ndrivers/net/ppp/ppp_async.c-106-\t.start_xmit = ppp_async_send,\n--\ndrivers/net/ppp/ppp_synctty.c=89=static void ppp_sync_input(struct syncppp ap, const u8 buf, const u8 flags,\n--\ndrivers/net/ppp/ppp_synctty.c-91-\ndrivers/net/ppp/ppp_synctty.c:92:static const struct ppp_channel_ops sync_ops = {\ndrivers/net/ppp/ppp_synctty.c-93-\t.start_xmit = ppp_sync_send,\n--\ndrivers/net/ppp/pppoe.c=88=static const struct proto_ops pppoe_ops;\ndrivers/net/ppp/pppoe.c:89:static const struct ppp_channel_ops pppoe_chan_ops;\ndrivers/net/ppp/pppoe.c-90-\n--\ndrivers/net/ppp/pppoe.c=896=static int pppoe_fill_forward_path(struct net_device_path_ctx ctx,\n--\ndrivers/net/ppp/pppoe.c-918-\ndrivers/net/ppp/pppoe.c:919:static const struct ppp_channel_ops pppoe_chan_ops = {\ndrivers/net/ppp/pppoe.c-920-\t.start_xmit = pppoe_xmit,\n--\ndrivers/net/ppp/pptp.c=49=static struct proto pptp_sk_proto __read_mostly;\ndrivers/net/ppp/pptp.c:50:static const struct ppp_channel_ops pptp_chan_ops;\ndrivers/net/ppp/pptp.c-51-static const struct proto_ops pptp_ops;\n--\ndrivers/net/ppp/pptp.c=576=static int pptp_ppp_ioctl(void private, unsigned int cmd, unsigned long arg)\n--\ndrivers/net/ppp/pptp.c-605-\ndrivers/net/ppp/pptp.c:606:static const struct ppp_channel_ops pptp_chan_ops = {\ndrivers/net/ppp/pptp.c-607-\t.start_xmit = pptp_xmit,\n--\ninclude/linux/ppp_channel.h=25=struct ppp_channel;\ninclude/linux/ppp_channel.h-26-\ninclude/linux/ppp_channel.h:27:struct ppp_channel_ops {\ninclude/linux/ppp_channel.h-28-\t/ Send a packet (or multilink fragment) on this channel.\n--\ninclude/linux/ppp_channel.h=38=struct ppp_channel {\ninclude/linux/ppp_channel.h-39-\tvoid\t\tprivate;\t/ channel private data /\ninclude/linux/ppp_channel.h:40:\tconst struct ppp_channel_ops ops; /* operations for this channel /\ninclude/linux/ppp_channel.h-41-\tint\t\tmtu;\t\t/ max transmit packet size /\n--\nnet/atm/pppoatm.c=364=static int pppoatm_devppp_ioctl(void private, unsigned int cmd,\n--\nnet/atm/pppoatm.c-377-\nnet/atm/pppoatm.c:378:static const struct ppp_channel_ops pppoatm_ops = {\nnet/atm/pppoatm.c-379-\t.start_xmit = pppoatm_send,\n--\nnet/l2tp/l2tp_ppp.c=125=static int pppol2tp_xmit(void private, struct sk_buff skb);\nnet/l2tp/l2tp_ppp.c-126-\nnet/l2tp/l2tp_ppp.c:127:static const struct ppp_channel_ops pppol2tp_chan_ops = {\nnet/l2tp/l2tp_ppp.c-128-\t.start_xmit = pppol2tp_xmit,\n" }
5/2	2026/09/05 12:42	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 9470 output: 28 thoughts: 374 Thoughts: Fuzzing Decision for PPP/PPPoE Protocols Okay, let's break this down. First, the guidelines clearly state I can't just wave off any modification, even if it's labeled "no functional change" or "refactoring". If the code is touched and executable, it must be fuzzed. And these PPP and PPPoE protocols, along with their variations (PPTP, PPPoL2TP, PPPoATM, ppp_async, ppp_synctty), are definitely within scope. They are standard networking protocols/drivers. They're reachable via sockets and `/dev/ppp` ioctls – that's a direct entry point, so WorthFuzzing is absolutely `true`. Now, before I commit to fuzzing, I need the Kconfig dependencies. This is important: I need to know under what conditions these files are actually compiled into the kernel. So, I need to check the relevant Makefiles (specifically `drivers/net/ppp/Makefile`, `net/atm/Makefile`, and `net/l2tp/Makefile`) and grep for the specific config options that govern the inclusion of `drivers/net/ppp/ppp_async.c`, `drivers/net/ppp/ppp_generic.c`, `drivers/net/ppp/ppp_synctty.c`, `drivers/net/ppp/pppoe.c`, `drivers/net/ppp/pptp.c`, `net/atm/pppoatm.c`, and `net/l2tp/l2tp_ppp.c`. Once I have this information, I can make a more informed decision regarding the effort required to make this fuzzable.
6/2	2026/09/05 12:43	tool	grepper	0m Args: { "Expression": "ppp", "PathPrefix": "drivers/net/ppp/Makefile" } Results: { "Output": "drivers/net/ppp/Makefile-5-\ndrivers/net/ppp/Makefile:6:obj-$(CONFIG_PPP) += ppp_generic.o\ndrivers/net/ppp/Makefile:7:obj-$(CONFIG_PPP_ASYNC) += ppp_async.o\ndrivers/net/ppp/Makefile-8-obj-$(CONFIG_PPP_BSDCOMP) += bsd_comp.o\ndrivers/net/ppp/Makefile:9:obj-$(CONFIG_PPP_DEFLATE) += ppp_deflate.o\ndrivers/net/ppp/Makefile:10:obj-$(CONFIG_PPP_MPPE) += ppp_mppe.o\ndrivers/net/ppp/Makefile:11:obj-$(CONFIG_PPP_SYNC_TTY) += ppp_synctty.o\ndrivers/net/ppp/Makefile:12:obj-$(CONFIG_PPPOX) += pppox.o\ndrivers/net/ppp/Makefile:13:obj-$(CONFIG_PPPOE) += pppoe.o\ndrivers/net/ppp/Makefile-14-obj-$(CONFIG_PPTP) += pptp.o\n" }
7/2	2026/09/05 12:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 10509 output: 28 thoughts: 21 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Examining Build Configurations for ATM and L2TP Okay, time to get my hands dirty. I'm going to dive into the build system configurations, specifically the `net/atm/Makefile` and `net/l2tp/Makefile` files. My immediate goal is to understand how these modules are being built within the kernel tree, and, implicitly, how they're integrated. I need to see the dependencies, compiler flags, and any conditional build logic specific to these network protocol implementations. This will give me a better grasp of any nuances that exist in their build setup. I'm looking for clues about the overall network stack build strategy too. Any interesting directives there will be a bonus! I expect these files to reveal much about module options, perhaps exposing whether particular features are enabled or disabled by default, and how to control the build process for specific configurations. It's time to find out.
8/2	2026/09/05 12:43	tool	grepper	0m Args: { "Expression": "pppoatm", "PathPrefix": "net/atm/Makefile" } Results: { "Output": "net/atm/Makefile=10=atm-$(CONFIG_PROC_FS) += proc.o\nnet/atm/Makefile-11-\nnet/atm/Makefile:12:obj-$(CONFIG_PPPOATM) += pppoatm.o\n" }
9/2	2026/09/05 12:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 10835 output: 32 thoughts: 13 Thoughts: Here's my take on those thoughts, tailored for an expert audience: Diving into the L2TP Makefile Okay, so I'm thinking, time to crack open the `net/l2tp/Makefile`. This is where the rubber meets the road, where the kernel build process for the L2TP module is defined. I want to see how this thing is actually put together. I need to refresh my memory on the build options, any conditional compilation based on kernel versions or config flags, and potentially identify areas ripe for optimization or refactoring, depending on what I find. I'm especially interested in looking at dependencies – are there any potentially problematic relationships with other kernel subsystems? Time to get down in the weeds and see what secrets this Makefile holds.
10/2	2026/09/05 12:43	tool	grepper	0m Args: { "Expression": "l2tp_ppp", "PathPrefix": "net/l2tp/Makefile" } Results: { "Output": "net/l2tp/Makefile=8=CFLAGS_l2tp_core.o += -I$(src)\n--\nnet/l2tp/Makefile-10-# Build l2tp as modules if L2TP is M\nnet/l2tp/Makefile:11:obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_PPPOL2TP)) += l2tp_ppp.o\nnet/l2tp/Makefile-12-obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_IP)) += l2tp_ip.o\n" }
11/2	2026/09/05 12:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 11189 output: 59 thoughts: 51 Thoughts: Okay, here's my thought process on this, distilled into a first-person summary as you requested, geared towards a fellow expert: Kconfig Dive for PPP Configurations Alright, time to get my hands dirty and dive into the Kconfig files. I need to get a clear picture of how PPP (Point-to-Point Protocol) is configured within this project. Specifically, I'm interested in understanding the relationships and dependencies for various PPP sub-protocols and implementations. My target list is: `PPP`, `PPP_ASYNC`, `PPP_SYNC_TTY`, `PPPOE`, `PPTP`, `PPPOATM`, and `PPPOL2TP`. My immediate plan is to efficiently determine where these configurations live within the Kconfig hierarchy. No need to go hunting manually – a `grep` through the Kconfig files is the most straightforward approach to locate and pinpoint where each of those symbols is defined. That should quickly expose any dependencies, default settings, and potential build options related to these different PPP variations. I'll need to pay close attention to the context around each definition to understand any conditional logic that affects whether these features are enabled. This will give me a solid foundation for evaluating how these options fit together and ultimately how the system supports and enables the different PPP communication methods.
12/2	2026/09/05 12:43	tool	grepper	0m Args: { "Expression": "config (PPP\|PPP_ASYNC\|PPP_SYNC_TTY\|PPPOE\|PPTP\|PPPOATM\|PPPOL2TP)\\b", "PathPrefix": "drivers/net/ppp/Kconfig" } Results: { "Output": "drivers/net/ppp/Kconfig-5-\ndrivers/net/ppp/Kconfig:6:config PPP\ndrivers/net/ppp/Kconfig-7-\ttristate \"PPP (point-to-point protocol) support\"\n--\ndrivers/net/ppp/Kconfig=92=config PPP_MULTILINK\n--\ndrivers/net/ppp/Kconfig-103-\ndrivers/net/ppp/Kconfig:104:config PPPOATM\ndrivers/net/ppp/Kconfig-105-\ttristate \"PPP over ATM\"\n--\ndrivers/net/ppp/Kconfig=113=config PPPOX\n--\ndrivers/net/ppp/Kconfig-115-\ndrivers/net/ppp/Kconfig:116:config PPPOE\ndrivers/net/ppp/Kconfig-117-\ttristate \"PPP over Ethernet\"\n--\ndrivers/net/ppp/Kconfig=153=config PPPOE_HASH_BITS\n--\ndrivers/net/ppp/Kconfig-160-\ndrivers/net/ppp/Kconfig:161:config PPTP\ndrivers/net/ppp/Kconfig-162-\ttristate \"PPP over IPv4 (PPTP)\"\n--\ndrivers/net/ppp/Kconfig-172-\ndrivers/net/ppp/Kconfig:173:config PPPOL2TP\ndrivers/net/ppp/Kconfig-174-\ttristate \"PPP over L2TP\"\n--\ndrivers/net/ppp/Kconfig=181=if TTY\ndrivers/net/ppp/Kconfig-182-\ndrivers/net/ppp/Kconfig:183:config PPP_ASYNC\ndrivers/net/ppp/Kconfig-184-\ttristate \"PPP support for async serial ports\"\n--\ndrivers/net/ppp/Kconfig-195-\ndrivers/net/ppp/Kconfig:196:config PPP_SYNC_TTY\ndrivers/net/ppp/Kconfig-197-\ttristate \"PPP support for sync tty ports\"\n" }
13/2	2026/09/05 12:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 12071 output: 35 thoughts: 21 Thoughts: Here's my summary, as if I were thinking these thoughts: Analyzing Kconfig Dependencies Okay, so I've got these Kconfig entries highlighted, and my first move is to quickly assess their relationships. I need to understand what controls these settings. The most direct approach is always to look at the surrounding lines. I'm going to scan the context – a few lines above and below each highlighted entry – specifically searching for any "depends on" statements. Those dependencies are the key; they'll tell me precisely which other configurations must be enabled (or disabled) for these particular settings to even be considered, or to work correctly. It's the best first step in understanding the logic.
14/2	2026/09/05 12:43	tool	read-file	0m Args: { "File": "drivers/net/ppp/Kconfig", "FirstLine": 1, "LineCount": 100 } Results: { "Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\t#\n 3:\t# PPP network device configuration\n 4:\t#\n 5:\t\n 6:\tconfig PPP\n 7:\t\ttristate \"PPP (point-to-point protocol) support\"\n 8:\t\tselect SLHC\n 9:\t\thelp\n 10:\t\t PPP (Point to Point Protocol) is a newer and better SLIP. It serves\n 11:\t\t the same purpose: sending Internet traffic over telephone (and other\n 12:\t\t serial) lines. Ask your access provider if they support it, because\n 13:\t\t otherwise you can't use it; most Internet access providers these\n 14:\t\t days support PPP rather than SLIP.\n 15:\t\n 16:\t\t To use PPP, you need an additional program called pppd, available at\n 17:\t\t \u003chttps://ppp.samba.org\u003e. Make sure that you have the version of pppd\n 18:\t\t recommended in \u003cfile:Documentation/Changes\u003e.\n 19:\t\t The PPP option enlarges your kernel by about 16 KB.\n 20:\t\n 21:\t\t There are actually two versions of PPP: the traditional PPP for\n 22:\t\t asynchronous lines, such as regular analog phone lines, and\n 23:\t\t synchronous PPP which can be used over digital ISDN lines for\n 24:\t\t example. If you want to use PPP over phone lines or other\n 25:\t\t asynchronous serial lines, you need to say Y (or M) here and also to\n 26:\t\t the next option, \"PPP support for async serial ports\". For PPP over\n 27:\t\t synchronous lines, you should say Y (or M) here and to \"Support\n 28:\t\t synchronous PPP\", below.\n 29:\t\n 30:\t\t If you said Y to \"Version information on all symbols\" above, then\n 31:\t\t you cannot compile the PPP driver into the kernel; you can then only\n 32:\t\t compile it as a module. To compile this driver as a module, choose M\n 33:\t\t here. The module will be called ppp_generic.\n 34:\t\n 35:\tif PPP\n 36:\t\n 37:\tconfig PPP_BSDCOMP\n 38:\t\ttristate \"PPP BSD-Compress compression\"\n 39:\t\thelp\n 40:\t\t Support for the BSD-Compress compression method for PPP, which uses\n 41:\t\t the LZW compression method to compress each PPP packet before it is\n 42:\t\t sent over the wire. The machine at the other end of the PPP link\n 43:\t\t (usually your ISP) has to support the BSD-Compress compression\n 44:\t\t method as well for this to be useful. Even if they don't support it,\n 45:\t\t it is safe to say Y here.\n 46:\t\n 47:\t\t The PPP Deflate compression method (\"PPP Deflate compression\",\n 48:\t\t above) is preferable to BSD-Compress, because it compresses better\n 49:\t\t and is patent-free.\n 50:\t\n 51:\t\t Note that the BSD compression code will always be compiled as a\n 52:\t\t module; it is called bsd_comp and will show up in the directory\n 53:\t\t modules once you have said \"make modules\". If unsure, say N.\n 54:\t\n 55:\tconfig PPP_DEFLATE\n 56:\t\ttristate \"PPP Deflate compression\"\n 57:\t\tselect ZLIB_INFLATE\n 58:\t\tselect ZLIB_DEFLATE\n 59:\t\thelp\n 60:\t\t Support for the Deflate compression method for PPP, which uses the\n 61:\t\t Deflate algorithm (the same algorithm that gzip uses) to compress\n 62:\t\t each PPP packet before it is sent over the wire. The machine at the\n 63:\t\t other end of the PPP link (usually your ISP) has to support the\n 64:\t\t Deflate compression method as well for this to be useful. Even if\n 65:\t\t they don't support it, it is safe to say Y here.\n 66:\t\n 67:\t\t To compile this driver as a module, choose M here.\n 68:\t\n 69:\tconfig PPP_FILTER\n 70:\t\tbool \"PPP filtering\"\n 71:\t\thelp\n 72:\t\t Say Y here if you want to be able to filter the packets passing over\n 73:\t\t PPP interfaces. This allows you to control which packets count as\n 74:\t\t activity (i.e. which packets will reset the idle timer or bring up\n 75:\t\t a demand-dialed link) and which packets are to be dropped entirely.\n 76:\t\t You need to say Y here if you wish to use the pass-filter and\n 77:\t\t active-filter options to pppd.\n 78:\t\n 79:\t\t If unsure, say N.\n 80:\t\n 81:\tconfig PPP_MPPE\n 82:\t\ttristate \"PPP MPPE compression (encryption)\"\n 83:\t\tselect CRYPTO_LIB_ARC4\n 84:\t\tselect CRYPTO_LIB_SHA1\n 85:\t\thelp\n 86:\t\t Support for the MPPE Encryption protocol, as employed by the\n 87:\t\t Microsoft Point-to-Point Tunneling Protocol.\n 88:\t\n 89:\t\t See http://pptpclient.sourceforge.net/ for information on\n 90:\t\t configuring PPTP clients and servers to utilize this method.\n 91:\t\n 92:\tconfig PPP_MULTILINK\n 93:\t\tbool \"PPP multilink support\"\n 94:\t\thelp\n 95:\t\t PPP multilink is a protocol (defined in RFC 1990) which allows you\n 96:\t\t to combine several (logical or physical) lines into one logical PPP\n 97:\t\t connection, so that you can utilize your full bandwidth.\n 98:\t\n 99:\t\t This has to be supported at the other end as well and you need a\n 100:\t\t version of the pppd daemon which understands the multilink protocol.\n" }
15/2	2026/09/05 12:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 13836 output: 37 thoughts: 17 Thoughts: Here's a summary of my thought process, as if I were reading the provided text: Delving into `drivers/net/ppp/Kconfig` Okay, time to get a deeper understanding of this PPP configuration. I'm going to take a look at the rest of the `drivers/net/ppp/Kconfig` file. I'm hoping to get a clearer picture of how this is all set up, what the different options are, and how they relate to each other. This is crucial for maintaining and extending the networking stack. Let's see what gems we can unearth.
16/2	2026/09/05 12:43	tool	read-file	0m Args: { "File": "drivers/net/ppp/Kconfig", "FirstLine": 101, "LineCount": 105 } Results: { "Contents": " 101:\t\n 102:\t\t If unsure, say N.\n 103:\t\n 104:\tconfig PPPOATM\n 105:\t\ttristate \"PPP over ATM\"\n 106:\t\tdepends on ATM\n 107:\t\thelp\n 108:\t\t Support PPP (Point to Point Protocol) encapsulated in ATM frames.\n 109:\t\t This implementation does not yet comply with section 8 of RFC2364,\n 110:\t\t which can lead to bad results if the ATM peer loses state and\n 111:\t\t changes its encapsulation unilaterally.\n 112:\t\n 113:\tconfig PPPOX\n 114:\t\ttristate\n 115:\t\n 116:\tconfig PPPOE\n 117:\t\ttristate \"PPP over Ethernet\"\n 118:\t\tselect PPPOX\n 119:\t\thelp\n 120:\t\t Support for PPP over Ethernet.\n 121:\t\n 122:\t\t To work in client mode, pppd version 2.4.2 or later is required.\n 123:\t\t To work in server mode, the pppoe-server command from the RP-PPPoE\n 124:\t\t package is also required, available at\n 125:\t\t \u003chttps://dianne.skoll.ca/projects/rp-pppoe/\u003e.\n 126:\t\n 127:\tchoice\n 128:\t\tprompt \"Number of PPPoE hash bits\"\n 129:\t\tdefault PPPOE_HASH_BITS_4\n 130:\t\tdepends on PPPOE\n 131:\t\thelp\n 132:\t\t\tSelect the number of bits used for hashing PPPoE interfaces.\n 133:\t\n 134:\t\t\tLarger sizes reduces the risk of hash collisions at the cost\n 135:\t\t\tof slightly increased memory usage.\n 136:\t\n 137:\t\t\tThis hash table is on a per outer ethernet interface.\n 138:\t\n 139:\tconfig PPPOE_HASH_BITS_1\n 140:\t\tbool \"1 bit (2 buckets)\"\n 141:\t\n 142:\tconfig PPPOE_HASH_BITS_2\n 143:\t\tbool \"2 bits (4 buckets)\"\n 144:\t\n 145:\tconfig PPPOE_HASH_BITS_4\n 146:\t\tbool \"4 bits (16 buckets)\"\n 147:\t\n 148:\tconfig PPPOE_HASH_BITS_8\n 149:\t\tbool \"8 bits (256 buckets)\"\n 150:\t\n 151:\tendchoice\n 152:\t\n 153:\tconfig PPPOE_HASH_BITS\n 154:\t\tint\n 155:\t\tdefault 1 if PPPOE_HASH_BITS_1\n 156:\t\tdefault 2 if PPPOE_HASH_BITS_2\n 157:\t\tdefault 4 if PPPOE_HASH_BITS_4\n 158:\t\tdefault 8 if PPPOE_HASH_BITS_8\n 159:\t\tdefault 4\n 160:\t\n 161:\tconfig PPTP\n 162:\t\ttristate \"PPP over IPv4 (PPTP)\"\n 163:\t\tdepends on NET_IPGRE_DEMUX\n 164:\t\tselect PPPOX\n 165:\t\thelp\n 166:\t\t Support for PPP over IPv4.(Point-to-Point Tunneling Protocol)\n 167:\t\n 168:\t\t This driver requires pppd plugin to work in client mode or\n 169:\t\t modified pptpd (poptop) to work in server mode.\n 170:\t\t See http://accel-pptp.sourceforge.net/ for information how to\n 171:\t\t utilize this module.\n 172:\t\n 173:\tconfig PPPOL2TP\n 174:\t\ttristate \"PPP over L2TP\"\n 175:\t\tdepends on L2TP\n 176:\t\tselect PPPOX\n 177:\t\thelp\n 178:\t\t Support for PPP-over-L2TP socket family. L2TP is a protocol\n 179:\t\t used by ISPs and enterprises to tunnel PPP traffic over UDP\n 180:\t\t tunnels. L2TP is replacing PPTP for VPN uses.\n 181:\tif TTY\n 182:\t\n 183:\tconfig PPP_ASYNC\n 184:\t\ttristate \"PPP support for async serial ports\"\n 185:\t\tselect CRC_CCITT\n 186:\t\thelp\n 187:\t\t Say Y (or M) here if you want to be able to use PPP over standard\n 188:\t\t asynchronous serial ports, such as COM1 or COM2 on a PC. If you use\n 189:\t\t a modem (not a synchronous or ISDN modem) to contact your ISP, you\n 190:\t\t need this option.\n 191:\t\n 192:\t\t To compile this driver as a module, choose M here.\n 193:\t\n 194:\t\t If unsure, say Y.\n 195:\t\n 196:\tconfig PPP_SYNC_TTY\n 197:\t\ttristate \"PPP support for sync tty ports\"\n 198:\t\thelp\n 199:\t\t Say Y (or M) here if you want to be able to use PPP over synchronous\n 200:\t\t (HDLC) tty devices. These devices are often used for high-speed leased\n" }
17/2	2026/09/05 12:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 15443 output: 360 thoughts: 971 Thoughts: PPP Channel Refactoring Verification Okay, let's break this down systematically. I need to verify this PPP channel refactoring, ensuring the changes are sound and don't introduce any new vulnerabilities. First, I'll confirm the relevant configurations are enabled: `PPP`, `PPP_ASYNC`, `PPP_SYNC_TTY`, `PPPOE`, `PPTP`, `PPPOATM`, `PPPOL2TP`, along with their dependencies like `TTY`, `ATM`, `NET_IPGRE_DEMUX`, and `L2TP`. Next, I'll thoroughly examine the affected functions. My attention is drawn to those modified or directly calling the refactored operations. In `ppp_generic.c`, I'll look at `ppp_ioctl`, `ppp_fill_forward_path`, `ppp_push`, `ppp_mp_explode`, `__ppp_channel_push`, and `ppp_channel_bridge_input`. Then, in `ppp_async.c`, `ppp_async_ioctl` and `ppp_async_send`. Similarly, in `ppp_synctty.c`, `ppp_sync_ioctl` and `ppp_sync_send`; in `pppoe.c`, `pppoe_xmit` and `pppoe_fill_forward_path`; in `pptp.c`, `pptp_xmit` and `pptp_ppp_ioctl`; in `pppoatm.c`, `pppoatm_send` and `pppoatm_devppp_ioctl`; and finally, in `l2tp_ppp.c`, `pppol2tp_xmit`. I need to be absolutely certain these are the only functions touched by the change, and that the change is appropriately localized. These are all specific, non-ubiquitous functions implementing/handling the PPP channel operations that were refactored. I'll then review the required configs once more to ensure all necessary components are enabled. I'll also double-check the configuration names without the `CONFIG_` prefix to confirm they're accurate and consistent with the kernel's configuration system. I'll compile a complete list of "FocusSymbols" – all the functions identified above that have been modified as part of the interface refactoring – to be reviewed in depth: `ppp_async_ioctl`, `ppp_async_send`, `ppp_sync_ioctl`, `ppp_sync_send`, `pppoe_xmit`, `pppoe_fill_forward_path`, `pptp_xmit`, `pptp_ppp_ioctl`, `pppoatm_send`, `pppoatm_devppp_ioctl`, `pppol2tp_xmit`, `ppp_push`, `ppp_mp_explode`, `__ppp_channel_push`, `ppp_channel_bridge_input`, `ppp_ioctl`, and `ppp_fill_forward_path`. Crucially, I'll need to confirm that all these symbols are defined in .c files and are non-static (or at least, are static functions used as function pointers, hence needing addresses). In conclusion, the patch's core change involves refactoring the `ppp_channel_ops` interface to pass the channel's private pointer directly instead of the channel structure. This directly impacts `ppp_generic`, `ppp_async`, `ppp_synctty`, `pppoe`, `pptp`, `pppoatm`, and `l2tp_ppp`. These components are key networking drivers and exposed via sockets and `/dev/ppp` ioctls. Therefore, rigorous fuzzing is paramount to detect type safety issues, regressions, and ensure that no unforeseen behaviors are introduced due to the refactoring. Now I'll call `set-results`.
18/2	2026/09/05 12:43	tool	set-results	0m Args: { "EnableConfigs": [ "PPP", "PPP_ASYNC", "PPP_SYNC_TTY", "PPPOE", "PPTP", "PPPOATM", "PPPOL2TP", "ATM", "L2TP", "NET_IPGRE_DEMUX" ], "FocusSymbols": [ "ppp_async_ioctl", "ppp_async_send", "ppp_sync_ioctl", "ppp_sync_send", "pppoe_xmit", "pppoe_fill_forward_path", "pptp_xmit", "pptp_ppp_ioctl", "pppoatm_send", "pppoatm_devppp_ioctl", "pppol2tp_xmit", "ppp_push", "ppp_mp_explode", "__ppp_channel_push", "ppp_channel_bridge_input", "ppp_ioctl", "ppp_fill_forward_path" ], "Reasoning": "The patch refactors the ppp_channel_ops interface (start_xmit, ioctl, fill_forward_path) to pass the channel private pointer directly instead of struct ppp_channel. It updates the callers in ppp_generic as well as implementations across PPP channel modules (ppp_async, ppp_synctty, pppoe, pptp, pppoatm, pppol2tp). These networking drivers and protocols are reachable via sockets and /dev/ppp ioctls in standard virtualized environments and should be fuzzed to catch any regressions.", "WorthFuzzing": true } Results: { "EnableConfigs": [ "PPP", "PPP_ASYNC", "PPP_SYNC_TTY", "PPPOE", "PPTP", "PPPOATM", "PPPOL2TP", "ATM", "L2TP", "NET_IPGRE_DEMUX" ], "FocusSymbols": [ "ppp_async_ioctl", "ppp_async_send", "ppp_sync_ioctl", "ppp_sync_send", "pppoe_xmit", "pppoe_fill_forward_path", "pptp_xmit", "pptp_ppp_ioctl", "pppoatm_send", "pppoatm_devppp_ioctl", "pppol2tp_xmit", "ppp_push", "ppp_mp_explode", "__ppp_channel_push", "ppp_channel_bridge_input", "ppp_ioctl", "ppp_fill_forward_path" ], "Reasoning": "The patch refactors the ppp_channel_ops interface (start_xmit, ioctl, fill_forward_path) to pass the channel private pointer directly instead of struct ppp_channel. It updates the callers in ppp_generic as well as implementations across PPP channel modules (ppp_async, ppp_synctty, pppoe, pptp, pppoatm, pppol2tp). These networking drivers and protocols are reachable via sockets and /dev/ppp ioctls in standard virtualized environments and should be fuzzed to catch any regressions.", "WorthFuzzing": true }
19/1	2026/09/05 12:43	action	If	0m Args: { "WorthFuzzing": true } Results: null
20/2	2026/09/05 12:43	agent	kmsan-evaluator	0m Model: core Args: null Results: { "KMSANReasoning": "The patch is a signature refactoring across the PPP subsystem: `struct ppp_channel_ops` callbacks (`start_xmit`, `ioctl`, and `fill_forward_path`) are updated to accept the channel's `private` pointer directly instead of `struct ppp_channel `. This change does not introduce or modify any memory allocations, buffer initializations, stack variables, or copy operations to userspace. No uninitialized memory paths or info-leak risks are created. Standard bug detectors and KASAN are sufficient to catch any pointer-related regressions.", "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 2e25189b6b8060c044e56218c2a77a83e3f5f0b1 Author: syz-cluster <triage@syzkaller.com> Date: Sat Sep 5 12:42:49 2026 +0000 syz-cluster: applied patch under review diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c index ea7fe9608ffd6..e73b0fce86b91 100644 --- a/drivers/net/ppp/ppp_async.c +++ b/drivers/net/ppp/ppp_async.c @@ -91,13 +91,12 @@ MODULE_ALIAS_LDISC(N_PPP); * Prototypes. / static int ppp_async_encode(struct asyncppp ap); -static int ppp_async_send(struct ppp_channel chan, struct sk_buff skb); +static int ppp_async_send(void private, struct sk_buff skb); static int ppp_async_push(struct asyncppp ap); static void ppp_async_flush_output(struct asyncppp ap); static void ppp_async_input(struct asyncppp ap, const unsigned char buf, const u8 flags, int count); -static int ppp_async_ioctl(struct ppp_channel chan, unsigned int cmd, - unsigned long arg); +static int ppp_async_ioctl(void private, unsigned int cmd, unsigned long arg); static void ppp_async_process(struct tasklet_struct t); static void async_lcp_peek(struct asyncppp ap, unsigned char data, @@ -321,9 +320,9 @@ ppp_async_init(void) * The following routines provide the PPP channel interface. / static int -ppp_async_ioctl(struct ppp_channel chan, unsigned int cmd, unsigned long arg) +ppp_async_ioctl(void private, unsigned int cmd, unsigned long arg) { - struct asyncppp ap = chan->private; + struct asyncppp ap = private; void __user argp = (void __user )arg; int __user p = argp; int err, val; @@ -550,9 +549,9 @@ ppp_async_encode(struct asyncppp ap) at some later time. / static int -ppp_async_send(struct ppp_channel chan, struct sk_buff skb) +ppp_async_send(void private, struct sk_buff skb) { - struct asyncppp ap = chan->private; + struct asyncppp ap = private; ppp_async_push(ap); diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c index 1a610a18893ba..3b83ff8cf5895 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -790,7 +790,7 @@ static long ppp_ioctl(struct file file, unsigned int cmd, unsigned long arg) chan = pch->chan; err = -ENOTTY; if (chan && chan->ops->ioctl) - err = chan->ops->ioctl(chan, cmd, arg); + err = chan->ops->ioctl(chan->private, cmd, arg); mutex_unlock(&pch->chan_sem); } goto out; @@ -1603,7 +1603,7 @@ static int ppp_fill_forward_path(struct net_device_path_ctx ctx, if (!chan->ops->fill_forward_path) return -EOPNOTSUPP; - return chan->ops->fill_forward_path(ctx, path, chan); + return chan->ops->fill_forward_path(ctx, path, chan->private); } static const struct net_device_ops ppp_netdev_ops = { @@ -1932,7 +1932,7 @@ ppp_push(struct ppp ppp, struct sk_buff skb) goto out; } - ret = chan->ops->start_xmit(chan, skb); + ret = chan->ops->start_xmit(chan->private, skb); out: spin_unlock(&pch->downl); @@ -2142,7 +2142,7 @@ static int ppp_mp_explode(struct ppp ppp, struct sk_buff skb) / try to send it down the channel / chan = pch->chan; if (!skb_queue_empty(&pch->file.xq) \|\| - !chan->ops->start_xmit(chan, frag)) + !chan->ops->start_xmit(chan->private, frag)) skb_queue_tail(&pch->file.xq, frag); pch->had_frag = 1; p += flen; @@ -2175,7 +2175,7 @@ static void __ppp_channel_push(struct channel pch, struct ppp ppp) if (pch->chan) { while (!skb_queue_empty(&pch->file.xq)) { skb = skb_dequeue(&pch->file.xq); - if (!pch->chan->ops->start_xmit(pch->chan, skb)) { + if (!pch->chan->ops->start_xmit(pch->chan->private, skb)) { / put the packet back and try again later / skb_queue_head(&pch->file.xq, skb); break; @@ -2300,7 +2300,7 @@ static bool ppp_channel_bridge_input(struct channel pch, struct sk_buff skb) } skb_scrub_packet(skb, !net_eq(pch->chan_net, pchb->chan_net)); - if (!pchb->chan->ops->start_xmit(pchb->chan, skb)) + if (!pchb->chan->ops->start_xmit(pchb->chan->private, skb)) kfree_skb(skb); outl: diff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c index f87d43faeeab5..54d8402e18c4a 100644 --- a/drivers/net/ppp/ppp_synctty.c +++ b/drivers/net/ppp/ppp_synctty.c @@ -81,9 +81,8 @@ struct syncppp { Prototypes. / static struct sk_buff ppp_sync_txmunge(struct syncppp ap, struct sk_buff ); -static int ppp_sync_send(struct ppp_channel chan, struct sk_buff skb); -static int ppp_sync_ioctl(struct ppp_channel chan, unsigned int cmd, - unsigned long arg); +static int ppp_sync_send(void private, struct sk_buff skb); +static int ppp_sync_ioctl(void private, unsigned int cmd, unsigned long arg); static void ppp_sync_process(struct tasklet_struct t); static int ppp_sync_push(struct syncppp ap); static void ppp_sync_flush_output(struct syncppp ap); @@ -312,9 +311,9 @@ ppp_sync_init(void) The following routines provide the PPP channel interface. / static int -ppp_sync_ioctl(struct ppp_channel chan, unsigned int cmd, unsigned long arg) +ppp_sync_ioctl(void private, unsigned int cmd, unsigned long arg) { - struct syncppp ap = chan->private; + struct syncppp ap = private; int err, val; u32 accm[8]; void __user argp = (void __user )arg; @@ -491,9 +490,9 @@ ppp_sync_txmunge(struct syncppp ap, struct sk_buff skb) at some later time. / static int -ppp_sync_send(struct ppp_channel chan, struct sk_buff skb) +ppp_sync_send(void private, struct sk_buff skb) { - struct syncppp ap = chan->private; + struct syncppp ap = private; ppp_sync_push(ap); diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c index bf7414b46a260..7584535035257 100644 --- a/drivers/net/ppp/pppoe.c +++ b/drivers/net/ppp/pppoe.c @@ -841,9 +841,9 @@ static int pppoe_sendmsg(struct socket sock, struct msghdr m, sends PPP frame over PPPoE socket * **********************************************************************/ -static int pppoe_xmit(struct ppp_channel chan, struct sk_buff skb) +static int pppoe_xmit(void private, struct sk_buff skb) { - struct sock sk = chan->private; + struct sock sk = private; struct pppox_sock po = pppox_sk(sk); struct net_device dev = po->pppoe_dev; struct pppoe_hdr ph; @@ -895,9 +895,9 @@ static int pppoe_xmit(struct ppp_channel chan, struct sk_buff skb) static int pppoe_fill_forward_path(struct net_device_path_ctx ctx, struct net_device_path path, - const struct ppp_channel chan) + void private) { - struct sock sk = chan->private; + struct sock sk = private; struct pppox_sock po = pppox_sk(sk); struct net_device dev = po->pppoe_dev; diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c index a797a0606f6b4..8f7190d7067e9 100644 --- a/drivers/net/ppp/pptp.c +++ b/drivers/net/ppp/pptp.c @@ -146,9 +146,9 @@ static struct rtable pptp_route_output(const struct pppox_sock po, return ip_route_output_flow(net, fl4, sk); } -static int pptp_xmit(struct ppp_channel chan, struct sk_buff skb) +static int pptp_xmit(void private, struct sk_buff skb) { - struct sock sk = chan->private; + struct sock sk = private; struct pppox_sock po = pppox_sk(sk); struct net net = sock_net(sk); struct pptp_opt opt = &po->proto.pptp; @@ -573,10 +573,9 @@ static int pptp_create(struct net net, struct socket sock, int kern) return error; } -static int pptp_ppp_ioctl(struct ppp_channel chan, unsigned int cmd, - unsigned long arg) +static int pptp_ppp_ioctl(void private, unsigned int cmd, unsigned long arg) { - struct sock sk = chan->private; + struct sock sk = private; struct pppox_sock po = pppox_sk(sk); struct pptp_opt opt = &po->proto.pptp; void __user argp = (void __user )arg; diff --git a/include/linux/ppp_channel.h b/include/linux/ppp_channel.h index 2f63e9a6cc889..d9cfb8ef0ffac 100644 --- a/include/linux/ppp_channel.h +++ b/include/linux/ppp_channel.h @@ -27,12 +27,12 @@ struct ppp_channel; struct ppp_channel_ops { / Send a packet (or multilink fragment) on this channel. Returns 1 if it was accepted, 0 if not. / - int (start_xmit)(struct ppp_channel , struct sk_buff ); + int (start_xmit)(void , struct sk_buff ); / Handle an ioctl call that has come in via /dev/ppp. / - int (ioctl)(struct ppp_channel , unsigned int, unsigned long); + int (ioctl)(void , unsigned int, unsigned long); int (fill_forward_path)(struct net_device_path_ctx , struct net_device_path , - const struct ppp_channel ); + void ); }; struct ppp_channel { diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c index 6da52d12df68e..913324f9685f6 100644 --- a/net/atm/pppoatm.c +++ b/net/atm/pppoatm.c @@ -91,11 +91,6 @@ static inline struct pppoatm_vcc atmvcc_to_pvcc(const struct atm_vcc atmvcc) return (struct pppoatm_vcc ) (atmvcc->user_back); } -static inline struct pppoatm_vcc chan_to_pvcc(const struct ppp_channel chan) -{ - return (struct pppoatm_vcc ) (chan->private); -} - /* * We can't do this directly from our _pop handler, since the ppp code * doesn't want to be called in interrupt context, so we do it from @@ -286,9 +281,9 @@ static int pppoatm_may_send(struct pppoatm_vcc pvcc, int size) as success, just to be clear what we're really doing. / #define DROP_PACKET 1 -static int pppoatm_send(struct ppp_channel chan, struct sk_buff skb) +static int pppoatm_send(void private, struct sk_buff skb) { - struct pppoatm_vcc pvcc = chan_to_pvcc(chan); + struct pppoatm_vcc pvcc = private; struct atm_vcc vcc; int ret; @@ -366,16 +361,16 @@ static int pppoatm_send(struct ppp_channel chan, struct sk_buff skb) } /* This handles ioctls sent to the /dev/ppp interface / -static int pppoatm_devppp_ioctl(struct ppp_channel chan, unsigned int cmd, - unsigned long arg) +static int pppoatm_devppp_ioctl(void private, unsigned int cmd, + unsigned long arg) { + struct pppoatm_vcc pvcc = private; + switch (cmd) { case PPPIOCGFLAGS: - return put_user(chan_to_pvcc(chan)->flags, (int __user ) arg) - ? -EFAULT : 0; + return put_user(pvcc->flags, (int __user )arg) ? -EFAULT : 0; case PPPIOCSFLAGS: - return get_user(chan_to_pvcc(chan)->flags, (int __user ) arg) - ? -EFAULT : 0; + return get_user(pvcc->flags, (int __user )arg) ? -EFAULT : 0; } return -ENOTTY; } diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index ef8fdfaf051d4..c1cda1d7fbf6b 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -122,7 +122,7 @@ struct pppol2tp_session { struct sock __sk; / Copy of .sk, for cleanup / }; -static int pppol2tp_xmit(struct ppp_channel chan, struct sk_buff skb); +static int pppol2tp_xmit(void private, struct sk_buff skb); static const struct ppp_channel_ops pppol2tp_chan_ops = { .start_xmit = pppol2tp_xmit, @@ -327,9 +327,9 @@ static int pppol2tp_sendmsg(struct socket sock, struct msghdr m, the skb it supplied, not our cloned skb. So we take care to always * leave the original skb unfreed if we return an error. / -static int pppol2tp_xmit(struct ppp_channel chan, struct sk_buff skb) +static int pppol2tp_xmit(void private, struct sk_buff skb) { - struct sock sk = (struct sock )chan->private; + struct sock sk = private; struct l2tp_session session; struct l2tp_tunnel tunnel; int uhlen, headroom;
21/3	2026/09/05 12:43	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 6413 output: 19 thoughts: 652 Thoughts: Analyzing the PPP Channel Operations Patch Okay, let's dive into this patch and figure out if it warrants a dedicated KMSAN fuzzing session. My initial thought is to understand the changes first. The core of this patch seems to be refactoring the `struct ppp_channel_ops`. Specifically, the code now passes `void private` instead of `struct ppp_channel ` to functions like `start_xmit`, `ioctl`, and `fill_forward_path`. It appears the rationale is to simplify things by directly providing the private data associated with the channel. The patch appears to update all the relevant implementations across the various PPP drivers: `ppp_async.c`, `ppp_generic.c`, `ppp_synctty.c`, `pppoe.c`, `pptp.c`, `pppoatm.c`, and `l2tp_ppp.c`. Within `ppp_generic.c`, the patch consistently updates calls like `chan->ops->ioctl(chan, cmd, arg)` to `chan->ops->ioctl(chan->private, cmd, arg)` and similar substitutions for the other function pointers, including the `start_xmit` and `fill_forward_path` functions. Each channel implementation also updates the function parameter declarations to match this new `void private` argument. Now, my main concern is making sure this is complete. We need to verify that every* single implementation of these functions across the entire kernel tree has been updated correctly. Any missed instance or a misapplied change could lead to uninitialized memory being read or written. Therefore, I need to do a thorough grep across the kernel for `struct ppp_channel_ops` to ensure no stray implementations have been overlooked, and that all function prototypes are consistent with the changes in the patch. This is critical for catching potential issues. I need to make sure the patch covers the entire surface area of these changes.
22/3	2026/09/05 12:43	tool	grepper	0m Args: { "Expression": "ppp_channel_ops" } Results: { "Output": "drivers/net/ppp/ppp_async.c=102=static void async_lcp_peek(struct asyncppp ap, unsigned char data,\n--\ndrivers/net/ppp/ppp_async.c-104-\ndrivers/net/ppp/ppp_async.c:105:static const struct ppp_channel_ops async_ops = {\ndrivers/net/ppp/ppp_async.c-106-\t.start_xmit = ppp_async_send,\n--\ndrivers/net/ppp/ppp_synctty.c=89=static void ppp_sync_input(struct syncppp ap, const u8 buf, const u8 flags,\n--\ndrivers/net/ppp/ppp_synctty.c-91-\ndrivers/net/ppp/ppp_synctty.c:92:static const struct ppp_channel_ops sync_ops = {\ndrivers/net/ppp/ppp_synctty.c-93-\t.start_xmit = ppp_sync_send,\n--\ndrivers/net/ppp/pppoe.c=88=static const struct proto_ops pppoe_ops;\ndrivers/net/ppp/pppoe.c:89:static const struct ppp_channel_ops pppoe_chan_ops;\ndrivers/net/ppp/pppoe.c-90-\n--\ndrivers/net/ppp/pppoe.c=896=static int pppoe_fill_forward_path(struct net_device_path_ctx ctx,\n--\ndrivers/net/ppp/pppoe.c-918-\ndrivers/net/ppp/pppoe.c:919:static const struct ppp_channel_ops pppoe_chan_ops = {\ndrivers/net/ppp/pppoe.c-920-\t.start_xmit = pppoe_xmit,\n--\ndrivers/net/ppp/pptp.c=49=static struct proto pptp_sk_proto __read_mostly;\ndrivers/net/ppp/pptp.c:50:static const struct ppp_channel_ops pptp_chan_ops;\ndrivers/net/ppp/pptp.c-51-static const struct proto_ops pptp_ops;\n--\ndrivers/net/ppp/pptp.c=576=static int pptp_ppp_ioctl(void private, unsigned int cmd, unsigned long arg)\n--\ndrivers/net/ppp/pptp.c-605-\ndrivers/net/ppp/pptp.c:606:static const struct ppp_channel_ops pptp_chan_ops = {\ndrivers/net/ppp/pptp.c-607-\t.start_xmit = pptp_xmit,\n--\ninclude/linux/ppp_channel.h=25=struct ppp_channel;\ninclude/linux/ppp_channel.h-26-\ninclude/linux/ppp_channel.h:27:struct ppp_channel_ops {\ninclude/linux/ppp_channel.h-28-\t/ Send a packet (or multilink fragment) on this channel.\n--\ninclude/linux/ppp_channel.h=38=struct ppp_channel {\ninclude/linux/ppp_channel.h-39-\tvoid\t\tprivate;\t/ channel private data /\ninclude/linux/ppp_channel.h:40:\tconst struct ppp_channel_ops ops; /* operations for this channel /\ninclude/linux/ppp_channel.h-41-\tint\t\tmtu;\t\t/ max transmit packet size /\n--\nnet/atm/pppoatm.c=364=static int pppoatm_devppp_ioctl(void private, unsigned int cmd,\n--\nnet/atm/pppoatm.c-377-\nnet/atm/pppoatm.c:378:static const struct ppp_channel_ops pppoatm_ops = {\nnet/atm/pppoatm.c-379-\t.start_xmit = pppoatm_send,\n--\nnet/l2tp/l2tp_ppp.c=125=static int pppol2tp_xmit(void private, struct sk_buff skb);\nnet/l2tp/l2tp_ppp.c-126-\nnet/l2tp/l2tp_ppp.c:127:static const struct ppp_channel_ops pppol2tp_chan_ops = {\nnet/l2tp/l2tp_ppp.c-128-\t.start_xmit = pppol2tp_xmit,\n" }
23/3	2026/09/05 12:43	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 8607 output: 143 thoughts: 726 Thoughts: KMSAN Evaluation for PPP Channel Callback Refactoring Okay, so I've gone through and updated every single `ppp_channel_ops` instance in the kernel. Now, let's carefully evaluate this based on the KMSAN guidelines. Remember, the rule is clear: KMSAN is a resource hog. We only use it if KASAN and the usual suspects can't catch a potential issue. It's for those insidious, silent uninitialized memory bugs that KMSAN is specifically designed for. The criteria are pretty specific: is the patch touching kernel structures sent to userspace, conditional logic that might depend on uninitialized variables, the allocation/initialization of complex data structures with potential uninitialized fields, or bounds checks that could lead to reading uninitialized bytes? In this case, this patch is a clean refactoring of PPP channel callback signatures. We're changing the call structure from `chan->ops->func(chan, ...)` with the internal retrieval of `ap = chan->private` to simply passing `chan->private` directly to `chan->ops->func(chan->private, ...)`. That's it. Let's break this down: * Are we introducing or modifying kernel structures sent to userspace? Nope. The `chan->private` data is already being passed around and used as needed, and there's no change to what's sent to userspace. For example, `pppoatm_devppp_ioctl` still functions as it did. * Are there any new conditionals or branching that depend on potentially uninitialized variables? No. `chan->private` is already initialized on channel registration. It was already being dereferenced inside each callback prior to this change. * Are we allocating or initializing any new complex data structures with potentially uninitialized fields? Nope, not at all. * Are we messing with bounds checks in a way that could expose uninitialized data? No again. On the flip side, we know we don't need KMSAN if the change primarily risks out-of-bounds access, overflows, NULL pointer dereferences, or use-after-free – things KASAN and friends handle perfectly well. The code doesn't touch those issues. We're not introducing any new stack or heap structures that aren't fully zeroed or initialized (using the standard practices). The patch absolutely doesn't introduce any risk of uninitialized memory reads or information leaks to user space. Okay, let's do a quick final run-through to make it all crystal clear: 1. The patch refactors PPP channel callbacks (`start_xmit`, `ioctl`, `fill_forward_path`) to receive `chan->private` (`void `) instead of `struct ppp_channel `. 2. This is a purely functional/signature refactoring, with no changes to memory allocation, buffer initialization, memory copy bounds, or uninitialized variable usage. 3. Any potential issues resulting from pointer mismatches or NULL pointers would be caught by KASAN / standard sanitizers (e.g. NULL pointer dereference or type confusion if any). 4. There is no risk of uninitialized memory reads or information leaks to user space. So, the conclusion is clear. `NeedsKMSAN` should be set to `false`. Time to call `set-results`.
24/3	2026/09/05 12:43	tool	set-results	0m Args: { "KMSANReasoning": "The patch is a signature refactoring across the PPP subsystem: `struct ppp_channel_ops` callbacks (`start_xmit`, `ioctl`, and `fill_forward_path`) are updated to accept the channel's `private` pointer directly instead of `struct ppp_channel `. This change does not introduce or modify any memory allocations, buffer initializations, stack variables, or copy operations to userspace. No uninitialized memory paths or info-leak risks are created. Standard bug detectors and KASAN are sufficient to catch any pointer-related regressions.", "NeedsKMSAN": false } Results:* { "KMSANReasoning": "The patch is a signature refactoring across the PPP subsystem: `struct ppp_channel_ops` callbacks (`start_xmit`, `ioctl`, and `fill_forward_path`) are updated to accept the channel's `private` pointer directly instead of `struct ppp_channel *`. This change does not introduce or modify any memory allocations, buffer initializations, stack variables, or copy operations to userspace. No uninitialized memory paths or info-leak risks are created. Standard bug detectors and KASAN are sufficient to catch any pointer-related regressions.", "NeedsKMSAN": false }

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Tool Calls Summary:
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