AI Trajectory

null

{
  "EnableConfigs": [
    "IPV6"
  ],
  "FocusSymbols": [
    "tcp_connect",
    "tcp_conn_request",
    "tcp_make_synack",
    "tcp_v4_syn_recv_sock"
  ],
  "KMSANReasoning": "The patch modifies the calculation of the advertised TCP MSS by introducing `ip_dst_mtu_configured()` and `ip6_dst_mtu_configured()`. These functions read existing, initialized fields from routing and device structures (`dst_entry`, `rt6_info`, `fib6_info`, `net_device`, `inet6_dev`) to determine the configured MTU, ignoring ICMP-learned path MTU. There are no new allocations, no new structures passed to user space, and no changes that would expose uninitialized memory. Any potential issues introduced by this patch, such as NULL pointer dereferences or out-of-bounds accesses, would be caught by standard KASAN or other standard bug detectors. Therefore, a dedicated KMSAN fuzzing session is not required.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch modifies the calculation of the advertised TCP MSS in IPv4 and IPv6. It introduces `ip_dst_mtu_configured` and `ip6_dst_mtu_configured` to ignore ICMP-learned path MTU and instead use the configured route or device MTU. This affects the TCP MSS advertised during connection setup (SYN/SYN-ACK). The changes are in core networking and functionally alter how MSS is determined, which is worth fuzzing.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit c8d674b98c859c7f3a62c1cc4f7be9830dc85318\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Fri Aug 14 07:33:13 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/net/ip.h b/include/net/ip.h\nindex 7f2fe1a8401b1..a8f57b4f4aa23 100644\n--- a/include/net/ip.h\n+++ b/include/net/ip.h\n@@ -506,6 +506,31 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,\n \treturn res;\n }\n \n+/* Configured/administrative MTU of a route, for advertising the TCP MSS.\n+ *\n+ * Unlike ip_dst_mtu_maybe_forward(), this deliberately ignores the\n+ * ICMP-learned path MTU (rt-\u003ert_pmtu).  The advertised MSS bounds what the\n+ * peer may send to us and must reflect our receive capability (the device or\n+ * route-configured MTU), not a path MTU learned on the reverse (send)\n+ * direction, which may not apply to the peer-\u003eus path and outlives the fnhe\n+ * for the whole connection.  See RFC 2923 section 2.3 and the comment above\n+ * tcp_advertise_mss().\n+ */\n+static inline unsigned int ip_dst_mtu_configured(const struct dst_entry *dst)\n+{\n+\tunsigned int mtu, res;\n+\n+\trcu_read_lock();\n+\tmtu = dst_metric_raw(dst, RTAX_MTU);\n+\tif (!mtu)\n+\t\tmtu = READ_ONCE(dst_dev_rcu(dst)-\u003emtu);\n+\tmtu = min_t(unsigned int, mtu, IP_MAX_MTU);\n+\tres = mtu - lwtunnel_headroom(dst-\u003elwtstate, mtu);\n+\trcu_read_unlock();\n+\n+\treturn res;\n+}\n+\n static inline unsigned int ip_skb_dst_mtu(struct sock *sk,\n \t\t\t\t\t  const struct sk_buff *skb)\n {\ndiff --git a/include/net/ip6_route.h b/include/net/ip6_route.h\nindex 09ffe0f13ce75..ac1acc0b74368 100644\n--- a/include/net/ip6_route.h\n+++ b/include/net/ip6_route.h\n@@ -385,6 +385,43 @@ static inline unsigned int ip6_dst_mtu_maybe_forward(const struct dst_entry *dst\n \treturn mtu - lwtunnel_headroom(dst-\u003elwtstate, mtu);\n }\n \n+/* Configured/administrative MTU of a route, for advertising the TCP MSS.\n+ *\n+ * Unlike ip6_dst_mtu_maybe_forward(), this ignores any ICMPv6-learned path\n+ * MTU (which is kept on the RTF_CACHE exception route) and returns the MTU of\n+ * the underlying route (fib6_pmtu) or the egress device.  The advertised MSS\n+ * bounds what the peer may send to us and must reflect our receive\n+ * capability, not a path MTU learned on the reverse (send) direction.  See\n+ * RFC 2923 section 2.3 and the comment above tcp_advertise_mss().\n+ */\n+static inline unsigned int ip6_dst_mtu_configured(const struct dst_entry *dst)\n+{\n+\tconst struct rt6_info *rt = dst_rt6_info(dst);\n+\tconst struct fib6_info *from;\n+\tstruct inet6_dev *idev;\n+\tunsigned int mtu = 0;\n+\n+\trcu_read_lock();\n+\t/* IPv6 keeps the learned PMTU and the configured MTU in the same\n+\t * RTAX_MTU slot: the learned value sits on this (possibly RTF_CACHE)\n+\t * dst, the configured one on the underlying route.  Reach the latter\n+\t * via -\u003efrom (fib6_pmtu), populated by ip6_route_info_create().\n+\t */\n+\tfrom = rcu_dereference(rt-\u003efrom);\n+\tif (from)\n+\t\tmtu = from-\u003efib6_pmtu;\n+\tif (!mtu) {\n+\t\tmtu = IPV6_MIN_MTU;\n+\t\tidev = __in6_dev_get(dst_dev_rcu(dst));\n+\t\tif (idev)\n+\t\t\tmtu = max_t(unsigned int, mtu, READ_ONCE(idev-\u003ecnf.mtu6));\n+\t}\n+\trcu_read_unlock();\n+\n+\tmtu = min_t(unsigned int, mtu, IP6_MAX_MTU);\n+\treturn mtu - lwtunnel_headroom(dst-\u003elwtstate, mtu);\n+}\n+\n u32 ip6_mtu_from_fib6(const struct fib6_result *res,\n \t\t      const struct in6_addr *daddr,\n \t\t      const struct in6_addr *saddr);\ndiff --git a/net/ipv4/route.c b/net/ipv4/route.c\nindex fd688e1f879f5..46aa98c921833 100644\n--- a/net/ipv4/route.c\n+++ b/net/ipv4/route.c\n@@ -1334,8 +1334,8 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst)\n \n \trcu_read_lock();\n \tnet = dst_dev_net_rcu(dst);\n-\tadvmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,\n-\t\t\t\t   net-\u003eipv4.ip_rt_min_advmss);\n+\tadvmss = max_t(unsigned int, ip_dst_mtu_configured(dst) - header_size,\n+\t\t       net-\u003eipv4.ip_rt_min_advmss);\n \trcu_read_unlock();\n \n \treturn min(advmss, IPV4_MAX_PMTU - header_size);\ndiff --git a/net/ipv6/route.c b/net/ipv6/route.c\nindex 5968ce5ad1508..e2056bd0df3c4 100644\n--- a/net/ipv6/route.c\n+++ b/net/ipv6/route.c\n@@ -3261,7 +3261,7 @@ void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk)\n \n static unsigned int ip6_default_advmss(const struct dst_entry *dst)\n {\n-\tunsigned int mtu = dst6_mtu(dst);\n+\tunsigned int mtu = ip6_dst_mtu_configured(dst);\n \tstruct net *net;\n \n \tmtu -= sizeof(struct ipv6hdr) + sizeof(struct tcphdr);\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "IPV6"
  ],
  "FocusSymbols": [
    "tcp_connect",
    "tcp_conn_request",
    "tcp_make_synack",
    "tcp_v4_syn_recv_sock"
  ],
  "Reasoning": "The patch modifies the calculation of the advertised TCP MSS in IPv4 and IPv6. It introduces `ip_dst_mtu_configured` and `ip6_dst_mtu_configured` to ignore ICMP-learned path MTU and instead use the configured route or device MTU. This affects the TCP MSS advertised during connection setup (SYN/SYN-ACK). The changes are in core networking and functionally alter how MSS is determined, which is worth fuzzing.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
  even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
   Prefer non-static, non-inlined API entrypoint functions over internal static helper functions
   (which are inlined by the compiler and do not have distinct symbol addresses).
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs
   needed for Kbuild to compile the code statically into vmlinux. List them in the EnableConfigs
   output array, and DO NOT add a '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.

For your convenience, here is the diff of the changes:
commit c8d674b98c859c7f3a62c1cc4f7be9830dc85318
Author: syz-cluster <triage@syzkaller.com>
Date:   Fri Aug 14 07:33:13 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/net/ip.h b/include/net/ip.h
index 7f2fe1a8401b1..a8f57b4f4aa23 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -506,6 +506,31 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
 	return res;
 }
 
+/* Configured/administrative MTU of a route, for advertising the TCP MSS.
+ *
+ * Unlike ip_dst_mtu_maybe_forward(), this deliberately ignores the
+ * ICMP-learned path MTU (rt->rt_pmtu).  The advertised MSS bounds what the
+ * peer may send to us and must reflect our receive capability (the device or
+ * route-configured MTU), not a path MTU learned on the reverse (send)
+ * direction, which may not apply to the peer->us path and outlives the fnhe
+ * for the whole connection.  See RFC 2923 section 2.3 and the comment above
+ * tcp_advertise_mss().
+ */
+static inline unsigned int ip_dst_mtu_configured(const struct dst_entry *dst)
+{
+	unsigned int mtu, res;
+
+	rcu_read_lock();
+	mtu = dst_metric_raw(dst, RTAX_MTU);
+	if (!mtu)
+		mtu = READ_ONCE(dst_dev_rcu(dst)->mtu);
+	mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
+	res = mtu - lwtunnel_headroom(dst->lwtstate, mtu);
+	rcu_read_unlock();
+
+	return res;
+}
+
 static inline unsigned int ip_skb_dst_mtu(struct sock *sk,
 					  const struct sk_buff *skb)
 {
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 09ffe0f13ce75..ac1acc0b74368 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -385,6 +385,43 @@ static inline unsigned int ip6_dst_mtu_maybe_forward(const struct dst_entry *dst
 	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
 }
 
+/* Configured/administrative MTU of a route, for advertising the TCP MSS.
+ *
+ * Unlike ip6_dst_mtu_maybe_forward(), this ignores any ICMPv6-learned path
+ * MTU (which is kept on the RTF_CACHE exception route) and returns the MTU of
+ * the underlying route (fib6_pmtu) or the egress device.  The advertised MSS
+ * bounds what the peer may send to us and must reflect our receive
+ * capability, not a path MTU learned on the reverse (send) direction.  See
+ * RFC 2923 section 2.3 and the comment above tcp_advertise_mss().
+ */
+static inline unsigned int ip6_dst_mtu_configured(const struct dst_entry *dst)
+{
+	const struct rt6_info *rt = dst_rt6_info(dst);
+	const struct fib6_info *from;
+	struct inet6_dev *idev;
+	unsigned int mtu = 0;
+
+	rcu_read_lock();
+	/* IPv6 keeps the learned PMTU and the configured MTU in the same
+	 * RTAX_MTU slot: the learned value sits on this (possibly RTF_CACHE)
+	 * dst, the configured one on the underlying route.  Reach the latter
+	 * via ->from (fib6_pmtu), populated by ip6_route_info_create().
+	 */
+	from = rcu_dereference(rt->from);
+	if (from)
+		mtu = from->fib6_pmtu;
+	if (!mtu) {
+		mtu = IPV6_MIN_MTU;
+		idev = __in6_dev_get(dst_dev_rcu(dst));
+		if (idev)
+			mtu = max_t(unsigned int, mtu, READ_ONCE(idev->cnf.mtu6));
+	}
+	rcu_read_unlock();
+
+	mtu = min_t(unsigned int, mtu, IP6_MAX_MTU);
+	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
+}
+
 u32 ip6_mtu_from_fib6(const struct fib6_result *res,
 		      const struct in6_addr *daddr,
 		      const struct in6_addr *saddr);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index fd688e1f879f5..46aa98c921833 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1334,8 +1334,8 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
 
 	rcu_read_lock();
 	net = dst_dev_net_rcu(dst);
-	advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
-				   net->ipv4.ip_rt_min_advmss);
+	advmss = max_t(unsigned int, ip_dst_mtu_configured(dst) - header_size,
+		       net->ipv4.ip_rt_min_advmss);
 	rcu_read_unlock();
 
 	return min(advmss, IPV4_MAX_PMTU - header_size);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 5968ce5ad1508..e2056bd0df3c4 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3261,7 +3261,7 @@ void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk)
 
 static unsigned int ip6_default_advmss(const struct dst_entry *dst)
 {
-	unsigned int mtu = dst6_mtu(dst);
+	unsigned int mtu = ip6_dst_mtu_configured(dst);
 	struct net *net;
 
 	mtu -= sizeof(struct ipv6hdr) + sizeof(struct tcphdr);

gemini-3.1-pro-preview

null

null

							input: 3471
							output: 21
							thoughts: 236
						

**My Analysis of a Networking Stack Patch**

Okay, so I've got a patch here that's making a crucial change to how we handle Maximum Segment Size (MSS) advertisements in the TCP stack. It seems the core networking stack, specifically IPv4 and IPv6 routing, is being updated. The key is in these modifications to `ipv4_default_advmss` and `ip6_default_advmss`. They're now using these newly defined functions, `ip_dst_mtu_configured` and `ip6_dst_mtu_configured`, instead of the old direct MTU lookups (`ipv4_mtu` and `dst6_mtu`). That's a definite improvement in the long run.

This is immediately flagged as a prime candidate for fuzzing. Any change like this, especially within the IPv4 and IPv6 routing core, can open up a lot of interesting attack vectors. Now, the main functions I need to focus on are `ipv4_default_advmss` and `ip6_default_advmss` (both static, as I recall). I need to determine exactly where those are being utilized. I suspect they're being assigned to `dst_ops->default_advmss` or something similar, likely as part of the destination option for routing. The next step is a code search; I'll look for direct references to `ipv4_default_advmss` and `ip6_default_advmss` to see how the system is using these functions to calculate the MSS.

{
  "Expression": "ipv4_default_advmss"
}

{
  "Output": "net/ipv4/route.c=129=struct dst_entry\t*ipv4_dst_check(struct dst_entry *dst, u32 cookie);\nnet/ipv4/route.c:130:static unsigned int\t ipv4_default_advmss(const struct dst_entry *dst);\nnet/ipv4/route.c-131-INDIRECT_CALLABLE_SCOPE\n--\nnet/ipv4/route.c=154=static struct dst_ops ipv4_dst_ops = {\n--\nnet/ipv4/route.c-156-\t.check =\t\tipv4_dst_check,\nnet/ipv4/route.c:157:\t.default_advmss =\tipv4_default_advmss,\nnet/ipv4/route.c-158-\t.mtu =\t\t\tipv4_mtu,\n--\nnet/ipv4/route.c=1320=static void set_class_tag(struct rtable *rt, u32 tag)\n--\nnet/ipv4/route.c-1328-\nnet/ipv4/route.c:1329:static unsigned int ipv4_default_advmss(const struct dst_entry *dst)\nnet/ipv4/route.c-1330-{\n--\nnet/ipv4/route.c=2881=static struct dst_ops ipv4_dst_blackhole_ops = {\nnet/ipv4/route.c-2882-\t.family\t\t\t= AF_INET,\nnet/ipv4/route.c:2883:\t.default_advmss\t\t= ipv4_default_advmss,\nnet/ipv4/route.c-2884-\t.neigh_lookup\t\t= ipv4_neigh_lookup,\n"
}

gemini-3.1-pro-preview

null

null

							input: 4491
							output: 21
							thoughts: 10
						

Okay, here's my summary, expressed in the first person, assuming I'm an expert in the field and considering the prompt's provided "thought":

**Delving into IPv6 MSS Adjustment**

Alright, let's see, we're talking about `ip6_default_advmss`. Right. So, I immediately recognize this as a crucial parameter related to IPv6 Maximum Segment Size (MSS) and Path MTU Discovery (PMTUD), specifically at the system's default level. My mind races. I'm thinking about how this variable impacts the initial TCP connection establishment process. Essentially, it defines the *advertised* MSS value that the local system will suggest to a remote host during the TCP handshake, which then allows each end to negotiate how large of a packet size they can both use.

I’m already considering the scenarios where this setting is important. It's often the first hurdle when dealing with IPv6 fragmentation and Path MTU issues. If the default is set too high, we'll see a lot of fragmentation, which will impact performance. If it's too low, we might be underutilizing network bandwidth. A thoughtful value ensures smooth communication without introducing too much overhead.

I'm probably going to be using this parameter often during network optimizations. So, let’s consider: what are the implications on different network configurations, considering common MTU sizes like 1500 bytes for standard Ethernet versus larger MTUs in environments like jumbo frames or VPN tunnels? It's all about finding the sweet spot, striking that critical balance between efficiency and reliability, to allow seamless transfer. The system can often use ICMP messages to determine if there are issues, but a well-tuned value helps to mitigate potential issues before they arise.

{
  "Expression": "ip6_default_advmss"
}

{
  "Output": "net/ipv6/route.c=86=struct dst_entry\t*ip6_dst_check(struct dst_entry *dst, u32 cookie);\nnet/ipv6/route.c:87:static unsigned int\t ip6_default_advmss(const struct dst_entry *dst);\nnet/ipv6/route.c-88-INDIRECT_CALLABLE_SCOPE\n--\nnet/ipv6/route.c=249=static struct dst_ops ip6_dst_ops_template = {\n--\nnet/ipv6/route.c-253-\t.check\t\t\t=\tip6_dst_check,\nnet/ipv6/route.c:254:\t.default_advmss\t\t=\tip6_default_advmss,\nnet/ipv6/route.c-255-\t.mtu\t\t\t=\tip6_mtu,\n--\nnet/ipv6/route.c=268=static struct dst_ops ip6_dst_blackhole_ops = {\nnet/ipv6/route.c-269-\t.family\t\t\t= AF_INET6,\nnet/ipv6/route.c:270:\t.default_advmss\t\t= ip6_default_advmss,\nnet/ipv6/route.c-271-\t.neigh_lookup\t\t= ip6_dst_neigh_lookup,\n--\nnet/ipv6/route.c=3256=void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk)\n--\nnet/ipv6/route.c-3261-\nnet/ipv6/route.c:3262:static unsigned int ip6_default_advmss(const struct dst_entry *dst)\nnet/ipv6/route.c-3263-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 5331
							output: 18
							thoughts: 10
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Tracing `default_advmss`**

Okay, so the question is, where is this `default_advmss` function being called? Given my experience, I'm immediately thinking about how it fits into the larger architecture. I know this is likely a critical setting, probably related to Maximum Segment Size (MSS) in the context of advanced MSS configuration, or it could be some default or fallback value.

My initial line of attack is going to be a code search. I'll need to pinpoint all instances of the function name. I'm going to start with a global search of the codebase, using a tool like grep or ripgrep. I'll look for direct calls to `default_advmss` in the code. I'm also going to check if there are any symbolic links, aliases or any other similar forms that are referring to it as well.

Based on the surrounding code, I'll start to build a mental map of the possible call paths. Knowing where it's being used is key. I'm going to pay close attention to the context of each call to see how the returned value is used. Is it passed to a specific function, assigned to a variable, used in an arithmetic calculation? This will narrow down its purpose and how it's being integrated within the program.

I'll keep an eye out for any conditional logic that might dictate when `default_advmss` is used. Does it serve as a default value if another configuration setting isn't explicitly set? Or maybe it's used based on network conditions or hardware capabilities. I want to know the conditions under which its result is applied.

Finally, I'm expecting to find that `default_advmss` has some form of configurable interface. I'm curious what kind of environment or setup settings it might reference. Does it get overridden by user configurations? Is it tied into a particular module? This is the kind of stuff that will help me understand its role. Ultimately, I'm looking for a complete picture, a roadmap of this function's purpose within this project.

{
  "Expression": "default_advmss"
}

{
  "Output": "include/net/dst.h=185=dst_metric_advmss(const struct dst_entry *dst)\n--\ninclude/net/dst.h-189-\tif (!advmss)\ninclude/net/dst.h:190:\t\tadvmss = dst-\u003eops-\u003edefault_advmss(dst);\ninclude/net/dst.h-191-\n--\ninclude/net/dst_ops.h=15=struct dst_ops {\n--\ninclude/net/dst_ops.h-20-\tstruct dst_entry *\t(*check)(struct dst_entry *, __u32 cookie);\ninclude/net/dst_ops.h:21:\tunsigned int\t\t(*default_advmss)(const struct dst_entry *);\ninclude/net/dst_ops.h-22-\tunsigned int\t\t(*mtu)(const struct dst_entry *);\n--\nnet/ipv4/route.c=129=struct dst_entry\t*ipv4_dst_check(struct dst_entry *dst, u32 cookie);\nnet/ipv4/route.c:130:static unsigned int\t ipv4_default_advmss(const struct dst_entry *dst);\nnet/ipv4/route.c-131-INDIRECT_CALLABLE_SCOPE\n--\nnet/ipv4/route.c=154=static struct dst_ops ipv4_dst_ops = {\n--\nnet/ipv4/route.c-156-\t.check =\t\tipv4_dst_check,\nnet/ipv4/route.c:157:\t.default_advmss =\tipv4_default_advmss,\nnet/ipv4/route.c-158-\t.mtu =\t\t\tipv4_mtu,\n--\nnet/ipv4/route.c=1320=static void set_class_tag(struct rtable *rt, u32 tag)\n--\nnet/ipv4/route.c-1328-\nnet/ipv4/route.c:1329:static unsigned int ipv4_default_advmss(const struct dst_entry *dst)\nnet/ipv4/route.c-1330-{\n--\nnet/ipv4/route.c=2881=static struct dst_ops ipv4_dst_blackhole_ops = {\nnet/ipv4/route.c-2882-\t.family\t\t\t= AF_INET,\nnet/ipv4/route.c:2883:\t.default_advmss\t\t= ipv4_default_advmss,\nnet/ipv4/route.c-2884-\t.neigh_lookup\t\t= ipv4_neigh_lookup,\n--\nnet/ipv6/route.c=86=struct dst_entry\t*ip6_dst_check(struct dst_entry *dst, u32 cookie);\nnet/ipv6/route.c:87:static unsigned int\t ip6_default_advmss(const struct dst_entry *dst);\nnet/ipv6/route.c-88-INDIRECT_CALLABLE_SCOPE\n--\nnet/ipv6/route.c=249=static struct dst_ops ip6_dst_ops_template = {\n--\nnet/ipv6/route.c-253-\t.check\t\t\t=\tip6_dst_check,\nnet/ipv6/route.c:254:\t.default_advmss\t\t=\tip6_default_advmss,\nnet/ipv6/route.c-255-\t.mtu\t\t\t=\tip6_mtu,\n--\nnet/ipv6/route.c=268=static struct dst_ops ip6_dst_blackhole_ops = {\nnet/ipv6/route.c-269-\t.family\t\t\t= AF_INET6,\nnet/ipv6/route.c:270:\t.default_advmss\t\t= ip6_default_advmss,\nnet/ipv6/route.c-271-\t.neigh_lookup\t\t= ip6_dst_neigh_lookup,\n--\nnet/ipv6/route.c=3256=void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk)\n--\nnet/ipv6/route.c-3261-\nnet/ipv6/route.c:3262:static unsigned int ip6_default_advmss(const struct dst_entry *dst)\nnet/ipv6/route.c-3263-{\n--\nnet/xfrm/xfrm_policy.c=3994=static int xfrm_bundle_ok(struct xfrm_dst *first)\n--\nnet/xfrm/xfrm_policy.c-4061-\nnet/xfrm/xfrm_policy.c:4062:static unsigned int xfrm_default_advmss(const struct dst_entry *dst)\nnet/xfrm/xfrm_policy.c-4063-{\n--\nnet/xfrm/xfrm_policy.c=4111=int xfrm_policy_register_afinfo(const struct xfrm_policy_afinfo *afinfo, int family)\n--\nnet/xfrm/xfrm_policy.c-4126-\t\t\tdst_ops-\u003echeck = xfrm_dst_check;\nnet/xfrm/xfrm_policy.c:4127:\t\tif (likely(dst_ops-\u003edefault_advmss == NULL))\nnet/xfrm/xfrm_policy.c:4128:\t\t\tdst_ops-\u003edefault_advmss = xfrm_default_advmss;\nnet/xfrm/xfrm_policy.c-4129-\t\tif (likely(dst_ops-\u003emtu == NULL))\n"
}

gemini-3.1-pro-preview

null

null

							input: 7182
							output: 20
							thoughts: 36
						

Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:

**Decoding the `dst_metric_advmss` Call**

Alright, let's break this down. My immediate thought is, when I see `dst_metric_advmss`, my brain jumps to: "Okay, so this function is invoking `dst->ops->default_advmss(dst)`.  Classic interface pattern. But the critical question *always* arises - context is king in these scenarios, right?"

My internal monologue then asks, "Where the *hell* is `dst_metric_advmss` itself being called? What's the call stack? What process is invoking this function?" I need to understand the control flow, the surrounding conditions, and the *why* behind this particular call. Without that broader perspective, I'm just looking at a single thread in a very complex weave. Knowing where it's used gives the all-important context. The implications of this are important in my field, and I need to understand this to make informed decisions!

{
  "Expression": "dst_metric_advmss"
}

{
  "Output": "drivers/scsi/cxgbi/libcxgbi.c=1098=unsigned int cxgbi_sock_select_mss(struct cxgbi_sock *csk, unsigned int pmtu)\n--\ndrivers/scsi/cxgbi/libcxgbi.c-1102-\ndrivers/scsi/cxgbi/libcxgbi.c:1103:\tcsk-\u003eadvmss = dst_metric_advmss(dst);\ndrivers/scsi/cxgbi/libcxgbi.c-1104-\n--\ninclude/net/dst.h=184=static inline u32\ninclude/net/dst.h:185:dst_metric_advmss(const struct dst_entry *dst)\ninclude/net/dst.h-186-{\n--\nnet/ipv4/tcp_ipv4.c=1674=struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,\n--\nnet/ipv4/tcp_ipv4.c-1738-\ttcp_sync_mss(newsk, dst4_mtu(dst));\nnet/ipv4/tcp_ipv4.c:1739:\tnewtp-\u003eadvmss = tcp_mss_clamp(tcp_sk(sk), dst_metric_advmss(dst));\nnet/ipv4/tcp_ipv4.c-1740-\n--\nnet/ipv4/tcp_minisocks.c=431=void tcp_openreq_init_rwin(struct request_sock *req,\n--\nnet/ipv4/tcp_minisocks.c-442-\nnet/ipv4/tcp_minisocks.c:443:\tmss = tcp_mss_clamp(tp, dst_metric_advmss(dst));\nnet/ipv4/tcp_minisocks.c-444-\twindow_clamp = READ_ONCE(tp-\u003ewindow_clamp);\n--\nnet/ipv4/tcp_output.c=139=static __u16 tcp_advertise_mss(struct sock *sk)\n--\nnet/ipv4/tcp_output.c-145-\tif (dst) {\nnet/ipv4/tcp_output.c:146:\t\tunsigned int metric = dst_metric_advmss(dst);\nnet/ipv4/tcp_output.c-147-\n--\nnet/ipv4/tcp_output.c=3931=struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,\n--\nnet/ipv4/tcp_output.c-3974-\nnet/ipv4/tcp_output.c:3975:\tmss = tcp_mss_clamp(tp, dst_metric_advmss(dst));\nnet/ipv4/tcp_output.c-3976-\n--\nnet/ipv4/tcp_output.c=4101=static void tcp_connect_init(struct sock *sk)\n--\nnet/ipv4/tcp_output.c-4130-\t\tWRITE_ONCE(tp-\u003ewindow_clamp, dst_metric(dst, RTAX_WINDOW));\nnet/ipv4/tcp_output.c:4131:\ttp-\u003eadvmss = tcp_mss_clamp(tp, dst_metric_advmss(dst));\nnet/ipv4/tcp_output.c-4132-\n--\nnet/ipv6/tcp_ipv6.c=1382=static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,\n--\nnet/ipv6/tcp_ipv6.c-1489-\ttcp_sync_mss(newsk, dst6_mtu(dst));\nnet/ipv6/tcp_ipv6.c:1490:\tnewtp-\u003eadvmss = tcp_mss_clamp(tcp_sk(sk), dst_metric_advmss(dst));\nnet/ipv6/tcp_ipv6.c-1491-\n--\nnet/xfrm/xfrm_policy.c=4062=static unsigned int xfrm_default_advmss(const struct dst_entry *dst)\nnet/xfrm/xfrm_policy.c-4063-{\nnet/xfrm/xfrm_policy.c:4064:\treturn dst_metric_advmss(xfrm_dst_path(dst));\nnet/xfrm/xfrm_policy.c-4065-}\n"
}

gemini-3.1-pro-preview

null

null

							input: 8566
							output: 20
							thoughts: 175
						

**Focusing My Fuzzing Efforts for Maximum Impact**

Okay, let's see, `dst_metric_advmss` is the target here. I can see it's called from a few key places: `tcp_advertise_mss`, `tcp_connect_init`, `tcp_make_synack`, `tcp_openreq_init_rwin`, `tcp_v4_syn_recv_sock`, and `tcp_v6_syn_recv_sock`. That makes sense; they are all involved in TCP connection setup and MSS advertisement.

So, I should focus my fuzzing efforts on the entry points: `tcp_advertise_mss`, `tcp_connect_init`, `tcp_make_synack`, `tcp_v4_syn_recv_sock`, and `tcp_v6_syn_recv_sock`. Right, these are the places where interesting input is likely to hit `dst_metric_advmss`.

Hold on... `tcp_advertise_mss` and `tcp_connect_init` are both static, so that limits my options. I need to think about that. But `tcp_make_synack` is exported. Okay, let's verify that quickly.

{
  "Expression": "tcp_make_synack"
}

{
  "Output": "include/net/tcp.h=571=enum tcp_synack_type {\n--\ninclude/net/tcp.h-576-};\ninclude/net/tcp.h:577:struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,\ninclude/net/tcp.h-578-\t\t\t\tstruct request_sock *req,\n--\nnet/ipv4/tcp_ipv4.c=1162=static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst,\n--\nnet/ipv4/tcp_ipv4.c-1178-\nnet/ipv4/tcp_ipv4.c:1179:\tskb = tcp_make_synack(sk, dst, req, foc, synack_type, syn_skb);\nnet/ipv4/tcp_ipv4.c-1180-\n--\nnet/ipv4/tcp_output.c=3887=int tcp_send_synack(struct sock *sk)\n--\nnet/ipv4/tcp_output.c-3921-/**\nnet/ipv4/tcp_output.c:3922: * tcp_make_synack - Allocate one skb and build a SYNACK packet.\nnet/ipv4/tcp_output.c-3923- * @sk: listener socket\n--\nnet/ipv4/tcp_output.c-3930- */\nnet/ipv4/tcp_output.c:3931:struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,\nnet/ipv4/tcp_output.c-3932-\t\t\t\tstruct request_sock *req,\n--\nnet/ipv6/tcp_ipv6.c=550=static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,\n--\nnet/ipv6/tcp_ipv6.c-569-\nnet/ipv6/tcp_ipv6.c:570:\tskb = tcp_make_synack(sk, dst, req, foc, synack_type, syn_skb);\nnet/ipv6/tcp_ipv6.c-571-\n--\ntools/testing/selftests/net/tcp_ao/connect-deny.c=221=static void *client_fn(void *arg)\n--\ntools/testing/selftests/net/tcp_ao/connect-deny.c-249-\t/*\ntools/testing/selftests/net/tcp_ao/connect-deny.c:250:\t * XXX: The test doesn't increase any counters, see tcp_make_synack().\ntools/testing/selftests/net/tcp_ao/connect-deny.c-251-\t * Potentially, it can be speed up by setting sk_pair = -ETIMEDOUT\n"
}

gemini-3.1-pro-preview

null

null

							input: 9743
							output: 24
							thoughts: 41
						

Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Investigating TCP SYN-ACK Handling**

Hmm, so `tcp_make_synack` isn't a static function, which is interesting. It means there's some dynamic selection process going on when crafting those SYN-ACK packets. I need to understand that. And immediately, my mind jumps to the other key pieces: `tcp_v4_syn_recv_sock` and `tcp_v6_syn_recv_sock`. It's clear that the address family plays a role here, but is that *all* that dictates the call paths?

I suspect those `*_syn_recv_sock` functions handle the initial socket setup and the initial state transition. `tcp_make_synack` likely focuses on crafting the specific packet contents, possibly drawing upon the parameters set by those earlier functions or having its behavior influenced by the socket’s flags or options. I should also consider how the kernel handles connection queuing, and whether any of those structures are consulted during the SYN-ACK generation. I'll need to trace the calling chain and examine the data flow to get a complete picture. This feels like a good starting point for diving into the details.

{
  "Expression": "tcp_v4_syn_recv_sock"
}

{
  "Output": "include/net/tcp.h=560=void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);\ninclude/net/tcp.h:561:struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,\ninclude/net/tcp.h-562-\t\t\t\t  struct request_sock *req,\n--\nnet/ipv4/tcp_ipv4.c=1655=int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)\n--\nnet/ipv4/tcp_ipv4.c-1673- */\nnet/ipv4/tcp_ipv4.c:1674:struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,\nnet/ipv4/tcp_ipv4.c-1675-\t\t\t\t  struct request_sock *req,\n--\nnet/ipv4/tcp_ipv4.c=2358=const struct inet_connection_sock_af_ops ipv4_specific = {\n--\nnet/ipv4/tcp_ipv4.c-2362-\t.conn_request\t   = tcp_v4_conn_request,\nnet/ipv4/tcp_ipv4.c:2363:\t.syn_recv_sock\t   = tcp_v4_syn_recv_sock,\nnet/ipv4/tcp_ipv4.c-2364-\t.net_header_len\t   = sizeof(struct iphdr),\n--\nnet/ipv6/tcp_ipv6.c=1337=static void tcp_v6_restore_cb(struct sk_buff *skb)\n--\nnet/ipv6/tcp_ipv6.c-1346-\nnet/ipv6/tcp_ipv6.c:1347:/* Called from tcp_v4_syn_recv_sock() for v6_mapped children. */\nnet/ipv6/tcp_ipv6.c-1348-static void tcp_v6_mapped_child_init(struct sock *newsk, const struct sock *sk)\n--\nnet/ipv6/tcp_ipv6.c-1372-\nnet/ipv6/tcp_ipv6.c:1373:\t/* tcp_v4_syn_recv_sock() has initialized newinet-\u003emc_{index,ttl} */\nnet/ipv6/tcp_ipv6.c-1374-\tnewnp-\u003emcast_oif   = newinet-\u003emc_index;\n--\nnet/ipv6/tcp_ipv6.c=1382=static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,\n--\nnet/ipv6/tcp_ipv6.c-1404-\tif (skb-\u003eprotocol == htons(ETH_P_IP))\nnet/ipv6/tcp_ipv6.c:1405:\t\treturn tcp_v4_syn_recv_sock(sk, skb, req, dst,\nnet/ipv6/tcp_ipv6.c-1406-\t\t\t\t\t    req_unhash, own_req,\n"
}

gemini-3.1-pro-preview

null

null

							input: 10862
							output: 24
							thoughts: 83
						

Here's my thought process, as requested:

**Investigating TCPv6 Socket Handling**

Okay, so I'm looking at some TCP code, probably kernel-level stuff, and I see these functions: `tcp_v4_syn_recv_sock` and `tcp_v6_syn_recv_sock`. My initial thought is, "Right, those sound like they handle SYN packets, the initial connection request, for TCPv4 and TCPv6 respectively." I'm also noticing that they are likely exported, or at least visible outside their own source file. Makes sense, because these functions are key to accepting new connections.

Hang on a second…I thought I saw something about `tcp_v6_syn_recv_sock` being *static*. That’s odd. If it's static, it wouldn't be exported, which means it can't be used outside of the file it's declared in. This requires closer inspection. Let's dig deeper. The likely place to find it is `net/ipv6/tcp_ipv6.c`. I need to verify whether the source I'm looking at matches my expectations. Gotta check that specific source file and confirm whether `tcp_v6_syn_recv_sock` is indeed static or not. This will provide a critical piece of the puzzle regarding IPv6 TCP connection handling.

{
  "Expression": "tcp_v6_syn_recv_sock"
}

{
  "Output": "net/ipv6/syncookies.c=174=struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)\n--\nnet/ipv6/syncookies.c-229-\t * We need to lookup the dst_entry to get the correct window size.\nnet/ipv6/syncookies.c:230:\t * This is taken from tcp_v6_syn_recv_sock.  Somebody please enlighten\nnet/ipv6/syncookies.c-231-\t * me if there is a preferred way.\n--\nnet/ipv6/tcp_ipv6.c=1348=static void tcp_v6_mapped_child_init(struct sock *newsk, const struct sock *sk)\n--\nnet/ipv6/tcp_ipv6.c-1381-\nnet/ipv6/tcp_ipv6.c:1382:static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,\nnet/ipv6/tcp_ipv6.c-1383-\t\t\t\t\t struct request_sock *req,\n--\nnet/ipv6/tcp_ipv6.c=2007=const struct inet_connection_sock_af_ops ipv6_specific = {\n--\nnet/ipv6/tcp_ipv6.c-2011-\t.conn_request\t   = tcp_v6_conn_request,\nnet/ipv6/tcp_ipv6.c:2012:\t.syn_recv_sock\t   = tcp_v6_syn_recv_sock,\nnet/ipv6/tcp_ipv6.c-2013-\t.net_header_len\t   = sizeof(struct ipv6hdr),\n--\nnet/ipv6/tcp_ipv6.c=2038=static const struct inet_connection_sock_af_ops ipv6_mapped = {\n--\nnet/ipv6/tcp_ipv6.c-2042-\t.conn_request\t   = tcp_v6_conn_request,\nnet/ipv6/tcp_ipv6.c:2043:\t.syn_recv_sock\t   = tcp_v6_syn_recv_sock,\nnet/ipv6/tcp_ipv6.c-2044-\t.net_header_len\t   = sizeof(struct iphdr),\n"
}

gemini-3.1-pro-preview

null

null

							input: 11841
							output: 19
							thoughts: 74
						

**Analyzing TCP Connection Initialization**

Okay, so I'm diving into this TCP connection setup and I'm starting to zero in on the relevant code. `tcp_v6_syn_recv_sock` is clearly static, which means it's probably not the core area I need to investigate further right now. I'm going to shift my focus to `tcp_v4_syn_recv_sock` and the function `tcp_make_synack` – those seem like more promising candidates for understanding the initial handshake.

Just a quick check...what about `tcp_connect_init`? Oh, it's also static. Alright, that simplifies things a bit. No need to chase down its internals just yet. My next step is to pinpoint where `tcp_connect_init` is actually *called*. Knowing its context will give me a better understanding of how it fits into the broader connection initiation process and potentially reveal some hidden assumptions or dependencies. Let's see what the call graph tells me.

{
  "Expression": "tcp_connect_init"
}

{
  "Output": "Documentation/networking/net_cachelines/inet_connection_sock.rst=16=struct timer_list                   icsk_keepalive_timer\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:17:u32                                 icsk_rto               read_write                              tcp_cwnd_validate,tcp_schedule_lo...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-18-u32                                 icsk_rto_min\n--\nDocumentation/networking/net_cachelines/inet_connection_sock.rst=20=u32                                 icsk_delack_max\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:21:u32                                 icsk_pmtu_cookie       read_write                              tcp_sync_mss,tcp_current_mss,tcp_...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:22:struct tcp_congestion_ops           icsk_ca_ops            read_write                              tcp_cwnd_validate,tcp_tso_segs,tc...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:23:struct inet_connection_sock_af_ops  icsk_af_ops            read_mostly                             tcp_finish_connect,tcp_send_syn_d...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-24-struct tcp_ulp_ops*                 icsk_ulp_ops\n--\nDocumentation/networking/net_cachelines/inet_connection_sock.rst=28=u8:1                                icsk_ca_setsockopt\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:29:u8:1                                icsk_ca_dst_locked     write_mostly                            tcp_ca_dst_init,tcp_connect_init,...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:30:u8                                  icsk_retransmits       write_mostly                            tcp_connect_init,tcp_connect\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-31-u8                                  icsk_pending           read_write                              inet_csk_reset_xmit_timer,tcp_con...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:32:u8                                  icsk_backoff           write_mostly                            tcp_write_queue_purge,tcp_connect...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-33-u8                                  icsk_syn_retries\n--\nDocumentation/networking/net_cachelines/inet_connection_sock.rst=41=struct icsk_ack_u32                 lrcvtime               read_write                              tcp_finish_connect,tcp_connect,tc...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:42:struct icsk_ack_u16                 rcv_mss                write_mostly        read_mostly         __tcp_select_window,__tcp_cleanup...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:43:struct icsk_mtup_int                search_high            read_write                              tcp_mtup_init,tcp_sync_mss,tcp_co...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:44:struct icsk_mtup_int                search_low             read_write                              tcp_mtu_probe,tcp_mtu_check_repro...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:45:struct icsk_mtup_u32:31             probe_size             read_write                              tcp_mtup_init,tcp_connect_init,__...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:46:struct icsk_mtup_u32:1              enabled                read_write                              tcp_mtup_init,tcp_sync_mss,tcp_co...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:47:struct icsk_mtup_u32                probe_timestamp        read_write                              tcp_mtup_init,tcp_connect_init,tc...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-48-u32                                 icsk_probes_tstamp\n--\nnet/ipv4/tcp_output.c=4081=static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst)\n--\nnet/ipv4/tcp_output.c-4100-/* Do all connect socket setups that can be done AF independent. */\nnet/ipv4/tcp_output.c:4101:static void tcp_connect_init(struct sock *sk)\nnet/ipv4/tcp_output.c-4102-{\n--\nnet/ipv4/tcp_output.c=4298=int tcp_connect(struct sock *sk)\n--\nnet/ipv4/tcp_output.c-4359-\nnet/ipv4/tcp_output.c:4360:\ttcp_connect_init(sk);\nnet/ipv4/tcp_output.c-4361-\n"
}

gemini-3.1-pro-preview

null

null

							input: 13414
							output: 17
							thoughts: 61
						

**Analyzing TCP Connection Functions**

Okay, so `tcp_connect` is definitely exported, which immediately makes it a key function to investigate. This means my focus for now should be on functions like `tcp_connect` itself, along with related processes such as `tcp_make_synack` and `tcp_v4_syn_recv_sock`. It's worth confirming that `tcp_connect` is indeed accessible externally, as this would provide a vital entry point for my analysis. Let's start by delving into `tcp_connect`.

{
  "Expression": "tcp_connect"
}

{
  "Output": "\nFull output is too long, showing 500 out of 664 lines.\nUse more precise expression if possible.\n\nDocumentation/networking/net_cachelines/inet_connection_sock.rst=9=Type                                Name                   fastpath_tx_access  fastpath_rx_access  comment\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-10-=================================== ====================== =================== =================== =================================...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:11:struct inet_sock                    icsk_inet              read_mostly         read_mostly         tcp_init_buffer_space,tcp_init_tr...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-12-struct request_sock_queue           icsk_accept_queue\n--\nDocumentation/networking/net_cachelines/inet_connection_sock.rst=14=struct inet_bind2_bucket            icsk_bind2_hash        read_mostly                             tcp_set_state,inet_put_port\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:15:struct timer_list                   icsk_delack_timer      read_mostly                             inet_csk_reset_xmit_timer,tcp_con...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-16-struct timer_list                   icsk_keepalive_timer\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:17:u32                                 icsk_rto               read_write                              tcp_cwnd_validate,tcp_schedule_lo...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-18-u32                                 icsk_rto_min\n--\nDocumentation/networking/net_cachelines/inet_connection_sock.rst=20=u32                                 icsk_delack_max\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:21:u32                                 icsk_pmtu_cookie       read_write                              tcp_sync_mss,tcp_current_mss,tcp_...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:22:struct tcp_congestion_ops           icsk_ca_ops            read_write                              tcp_cwnd_validate,tcp_tso_segs,tc...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:23:struct inet_connection_sock_af_ops  icsk_af_ops            read_mostly                             tcp_finish_connect,tcp_send_syn_d...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-24-struct tcp_ulp_ops*                 icsk_ulp_ops\n--\nDocumentation/networking/net_cachelines/inet_connection_sock.rst=26=u8:5                                icsk_ca_state          read_write                              tcp_cwnd_application_limited,tcp_...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:27:u8:1                                icsk_ca_initialized    read_write                              tcp_init_transfer,tcp_init_conges...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-28-u8:1                                icsk_ca_setsockopt\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:29:u8:1                                icsk_ca_dst_locked     write_mostly                            tcp_ca_dst_init,tcp_connect_init,...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:30:u8                                  icsk_retransmits       write_mostly                            tcp_connect_init,tcp_connect\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:31:u8                                  icsk_pending           read_write                              inet_csk_reset_xmit_timer,tcp_con...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:32:u8                                  icsk_backoff           write_mostly                            tcp_write_queue_purge,tcp_connect...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-33-u8                                  icsk_syn_retries\n--\nDocumentation/networking/net_cachelines/inet_connection_sock.rst=40=struct icsk_ack_u8                  ato                    read_mostly         write_mostly        tcp_dec_quickack_mode,tcp_event_a...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:41:struct icsk_ack_u32                 lrcvtime               read_write                              tcp_finish_connect,tcp_connect,tc...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:42:struct icsk_ack_u16                 rcv_mss                write_mostly        read_mostly         __tcp_select_window,__tcp_cleanup...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:43:struct icsk_mtup_int                search_high            read_write                              tcp_mtup_init,tcp_sync_mss,tcp_co...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:44:struct icsk_mtup_int                search_low             read_write                              tcp_mtu_probe,tcp_mtu_check_repro...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:45:struct icsk_mtup_u32:31             probe_size             read_write                              tcp_mtup_init,tcp_connect_init,__...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:46:struct icsk_mtup_u32:1              enabled                read_write                              tcp_mtup_init,tcp_sync_mss,tcp_co...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst:47:struct icsk_mtup_u32                probe_timestamp        read_write                              tcp_mtup_init,tcp_connect_init,tc...\nDocumentation/networking/net_cachelines/inet_connection_sock.rst-48-u32                                 icsk_probes_tstamp\n--\nDocumentation/networking/net_cachelines/inet_sock.rst=9=Type                     Name                  fastpath_tx_access  fastpath_rx_access  comment\nDocumentation/networking/net_cachelines/inet_sock.rst-10-======================== ===================== =================== =================== ========================================================...\nDocumentation/networking/net_cachelines/inet_sock.rst:11:struct sock              sk                    read_mostly         read_mostly         tcp_init_buffer_space,tcp_init_transfer,tcp_finish_conne...\nDocumentation/networking/net_cachelines/inet_sock.rst-12-struct ipv6_pinfo*       pinet6\n--\ndrivers/net/ethernet/qlogic/qed/qed_hsi.h=9263=struct iwarp_mpa_offload_ramrod_data {\n--\ndrivers/net/ethernet/qlogic/qed/qed_hsi.h-9266-\tu8 mode;\ndrivers/net/ethernet/qlogic/qed/qed_hsi.h:9267:\tu8 tcp_connect_side;\ndrivers/net/ethernet/qlogic/qed/qed_hsi.h-9268-\tu8 rtr_pref;\n--\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c=819=qed_iwarp_mpa_offload(struct qed_hwfn *p_hwfn, struct qed_iwarp_ep *ep)\n--\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c-873-\t\t\toffsetof(struct qed_iwarp_ep_memory, in_pdata);\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c:874:\tp_mpa_ramrod-\u003etcp_connect_side = ep-\u003econnect_mode;\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c-875-\tDMA_REGPAIR_LE(p_mpa_ramrod-\u003eincoming_ulp_buffer.addr,\n--\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c=2957=static void\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c:2958:qed_iwarp_tcp_connect_unsuccessful(struct qed_hwfn *p_hwfn,\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c-2959-\t\t\t\t   struct qed_iwarp_ep *ep, u8 fw_return_code)\n--\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c=3019=qed_iwarp_connect_complete(struct qed_hwfn *p_hwfn,\n--\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c-3033-\t\telse\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c:3034:\t\t\tqed_iwarp_tcp_connect_unsuccessful(p_hwfn, ep,\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c-3035-\t\t\t\t\t\t\t   fw_return_code);\n--\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c-3039-\t\telse\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c:3040:\t\t\tqed_iwarp_tcp_connect_unsuccessful(p_hwfn, ep,\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.c-3041-\t\t\t\t\t\t\t   fw_return_code);\n--\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.h=112=struct qed_iwarp_ep {\n--\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.h-119-\tstruct qed_iwarp_cm_info cm_info;\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.h:120:\tenum tcp_connect_mode connect_mode;\ndrivers/net/ethernet/qlogic/qed/qed_iwarp.h-121-\tenum mpa_rtr_type rtr_type;\n--\ndrivers/net/hyperv/hyperv_net.h=1536=struct ndis_offload_params {\n--\ndrivers/net/hyperv/hyperv_net.h-1546-\tu8 lso_v2_ipv6;\ndrivers/net/hyperv/hyperv_net.h:1547:\tu8 tcp_connection_ip_v4;\ndrivers/net/hyperv/hyperv_net.h:1548:\tu8 tcp_connection_ip_v6;\ndrivers/net/hyperv/hyperv_net.h-1549-\tu32 flags;\n--\ndrivers/scsi/be2iscsi/be_cmds.h=1110=struct be_eq_delay_params_in {\n--\ndrivers/scsi/be2iscsi/be_cmds.h-1115-\ndrivers/scsi/be2iscsi/be_cmds.h:1116:struct tcp_connect_and_offload_in {\ndrivers/scsi/be2iscsi/be_cmds.h-1117-\tstruct be_cmd_req_hdr hdr;\n--\ndrivers/scsi/be2iscsi/be_cmds.h-1129-\ndrivers/scsi/be2iscsi/be_cmds.h:1130:struct tcp_connect_and_offload_in_v1 {\ndrivers/scsi/be2iscsi/be_cmds.h-1131-\tstruct be_cmd_req_hdr hdr;\n--\ndrivers/scsi/be2iscsi/be_cmds.h-1149-\ndrivers/scsi/be2iscsi/be_cmds.h:1150:struct tcp_connect_and_offload_out {\ndrivers/scsi/be2iscsi/be_cmds.h-1151-\tstruct be_cmd_resp_hdr hdr;\n--\ndrivers/scsi/be2iscsi/be_iscsi.c=1050=static int beiscsi_open_conn(struct iscsi_endpoint *ep,\n--\ndrivers/scsi/be2iscsi/be_iscsi.c-1055-\tstruct beiscsi_hba *phba = beiscsi_ep-\u003ephba;\ndrivers/scsi/be2iscsi/be_iscsi.c:1056:\tstruct tcp_connect_and_offload_out *ptcpcnct_out;\ndrivers/scsi/be2iscsi/be_iscsi.c-1057-\tstruct be_dma_mem nonemb_cmd;\n--\ndrivers/scsi/be2iscsi/be_iscsi.c-1080-\tif (is_chip_be2_be3r(phba))\ndrivers/scsi/be2iscsi/be_iscsi.c:1081:\t\treq_memsize = sizeof(struct tcp_connect_and_offload_in);\ndrivers/scsi/be2iscsi/be_iscsi.c-1082-\telse\ndrivers/scsi/be2iscsi/be_iscsi.c:1083:\t\treq_memsize = sizeof(struct tcp_connect_and_offload_in_v1);\ndrivers/scsi/be2iscsi/be_iscsi.c-1084-\n--\ndrivers/scsi/be2iscsi/be_iscsi.c-1125-\ndrivers/scsi/be2iscsi/be_iscsi.c:1126:\tptcpcnct_out = (struct tcp_connect_and_offload_out *)nonemb_cmd.va;\ndrivers/scsi/be2iscsi/be_iscsi.c-1127-\tbeiscsi_ep = ep-\u003edd_data;\n--\ndrivers/scsi/be2iscsi/be_mgmt.c=109=int mgmt_open_connection(struct beiscsi_hba *phba,\n--\ndrivers/scsi/be2iscsi/be_mgmt.c-119-\tstruct be_mcc_wrb *wrb;\ndrivers/scsi/be2iscsi/be_mgmt.c:120:\tstruct tcp_connect_and_offload_in_v1 *req;\ndrivers/scsi/be2iscsi/be_mgmt.c-121-\tunsigned short def_hdr_id;\n--\ninclude/linux/ceph/messenger.h=527=void ceph_encode_my_addr(struct ceph_messenger *msgr);\ninclude/linux/ceph/messenger.h-528-\ninclude/linux/ceph/messenger.h:529:int ceph_tcp_connect(struct ceph_connection *con);\ninclude/linux/ceph/messenger.h-530-int ceph_con_close_socket(struct ceph_connection *con);\n--\ninclude/linux/qed/nvmetcp_common.h=199=struct nvmetcp_host_cccid_itid_entry {\n--\ninclude/linux/qed/nvmetcp_common.h-202-\ninclude/linux/qed/nvmetcp_common.h:203:struct nvmetcp_connect_done_results {\ninclude/linux/qed/nvmetcp_common.h-204-\t__le16 icid;\n--\ninclude/linux/qed/tcp_common.h=17=struct ooo_opaque {\n--\ninclude/linux/qed/tcp_common.h-25-/* tcp connect mode enum */\ninclude/linux/qed/tcp_common.h:26:enum tcp_connect_mode {\ninclude/linux/qed/tcp_common.h-27-\tTCP_CONNECT_ACTIVE,\n--\ninclude/net/tcp.h=569=int tcp_v4_connect(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len);\ninclude/net/tcp.h:570:int tcp_connect(struct sock *sk);\ninclude/net/tcp.h-571-enum tcp_synack_type {\n--\ninclude/net/tcp.h=2103=struct tcp_fastopen_request {\n--\ninclude/net/tcp.h-2107-\tsize_t\t\t\t\tsize;\ninclude/net/tcp.h:2108:\tint\t\t\t\tcopied;\t/* queued in tcp_connect() */\ninclude/net/tcp.h-2109-\tstruct ubuf_info\t\t*uarg;\n--\nnet/ceph/messenger.c=417=static void set_sock_callbacks(struct socket *sock,\n--\nnet/ceph/messenger.c-434- */\nnet/ceph/messenger.c:435:int ceph_tcp_connect(struct ceph_connection *con)\nnet/ceph/messenger.c-436-{\n--\nnet/ceph/messenger_v1.c=1469=int ceph_con_v1_try_write(struct ceph_connection *con)\n--\nnet/ceph/messenger_v1.c-1493-\t\t     con, con-\u003estate);\nnet/ceph/messenger_v1.c:1494:\t\tret = ceph_tcp_connect(con);\nnet/ceph/messenger_v1.c-1495-\t\tif (ret \u003c 0) {\n--\nnet/ceph/messenger_v2.c=3354=int ceph_con_v2_try_write(struct ceph_connection *con)\n--\nnet/ceph/messenger_v2.c-3388-\nnet/ceph/messenger_v2.c:3389:\t\tret = ceph_tcp_connect(con);\nnet/ceph/messenger_v2.c-3390-\t\tif (ret) {\nnet/ceph/messenger_v2.c:3391:\t\t\tpr_err(\"ceph_tcp_connect failed: %d\\n\", ret);\nnet/ceph/messenger_v2.c-3392-\t\t\tcon-\u003eerror_msg = \"connect error\";\n--\nnet/ipv4/tcp.c=1051=int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,\n--\nnet/ipv4/tcp.c-1075-\tif (inet_test_bit(DEFER_CONNECT, sk)) {\nnet/ipv4/tcp.c:1076:\t\terr = tcp_connect(sk);\nnet/ipv4/tcp.c-1077-\t\t/* Same failure procedure as in tcp_v4/6_connect */\n--\nnet/ipv4/tcp_ao.c=1136=void tcp_ao_connect_init(struct sock *sk)\n--\nnet/ipv4/tcp_ao.c-1189-\t} else {\nnet/ipv4/tcp_ao.c:1190:\t\t/* Can't happen: tcp_connect() verifies that there's\nnet/ipv4/tcp_ao.c-1191-\t\t * at least one tcp-ao key that matches the remote peer.\n--\nnet/ipv4/tcp_ipv4.c=221=int tcp_v4_connect(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len)\n--\nnet/ipv4/tcp_ipv4.c-344-\nnet/ipv4/tcp_ipv4.c:345:\terr = tcp_connect(sk);\nnet/ipv4/tcp_ipv4.c-346-\n--\nnet/ipv4/tcp_output.c=4081=static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst)\n--\nnet/ipv4/tcp_output.c-4100-/* Do all connect socket setups that can be done AF independent. */\nnet/ipv4/tcp_output.c:4101:static void tcp_connect_init(struct sock *sk)\nnet/ipv4/tcp_output.c-4102-{\n--\nnet/ipv4/tcp_output.c-4180-\nnet/ipv4/tcp_output.c:4181:static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb)\nnet/ipv4/tcp_output.c-4182-{\n--\nnet/ipv4/tcp_output.c=4201=static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)\n--\nnet/ipv4/tcp_output.c-4258-\nnet/ipv4/tcp_output.c:4259:\ttcp_connect_queue_skb(sk, syn_data);\nnet/ipv4/tcp_output.c-4260-\tif (syn_data-\u003elen)\n--\nnet/ipv4/tcp_output.c-4297-/* Build a SYN and send it off. */\nnet/ipv4/tcp_output.c:4298:int tcp_connect(struct sock *sk)\nnet/ipv4/tcp_output.c-4299-{\n--\nnet/ipv4/tcp_output.c-4359-\nnet/ipv4/tcp_output.c:4360:\ttcp_connect_init(sk);\nnet/ipv4/tcp_output.c-4361-\n--\nnet/ipv4/tcp_output.c-4371-\t/* SYN eats a sequence byte, write_seq updated by\nnet/ipv4/tcp_output.c:4372:\t * tcp_connect_queue_skb().\nnet/ipv4/tcp_output.c-4373-\t */\n--\nnet/ipv4/tcp_output.c-4376-\ttp-\u003eretrans_stamp = tcp_time_stamp_ts(tp);\nnet/ipv4/tcp_output.c:4377:\ttcp_connect_queue_skb(sk, buff);\nnet/ipv4/tcp_output.c-4378-\ttcp_ecn_send_syn(sk, buff);\n--\nnet/ipv4/tcp_output.c-4403-}\nnet/ipv4/tcp_output.c:4404:EXPORT_SYMBOL(tcp_connect);\nnet/ipv4/tcp_output.c-4405-\n--\nnet/ipv6/tcp_ipv6.c=133=static int tcp_v6_connect(struct sock *sk, struct sockaddr_unsized *uaddr,\n--\nnet/ipv6/tcp_ipv6.c-345-\nnet/ipv6/tcp_ipv6.c:346:\terr = tcp_connect(sk);\nnet/ipv6/tcp_ipv6.c-347-\tif (err)\n--\nnet/mptcp/protocol.c=4085=static int mptcp_ioctl(struct sock *sk, int cmd, int *karg)\n--\nnet/mptcp/protocol.c-4117-\nnet/mptcp/protocol.c:4118:static int mptcp_connect(struct sock *sk, struct sockaddr_unsized *uaddr,\nnet/mptcp/protocol.c-4119-\t\t\t int addr_len)\n--\nnet/mptcp/protocol.c=4196=static struct proto mptcp_prot = {\n--\nnet/mptcp/protocol.c-4199-\t.init\t\t= mptcp_init_sock,\nnet/mptcp/protocol.c:4200:\t.connect\t= mptcp_connect,\nnet/mptcp/protocol.c-4201-\t.disconnect\t= mptcp_disconnect,\n--\nnet/rds/Makefile=13=obj-$(CONFIG_RDS_TCP) += rds_tcp.o\nnet/rds/Makefile:14:rds_tcp-y :=\t\ttcp.o tcp_connect.o tcp_listen.o tcp_recv.o \\\nnet/rds/Makefile-15-\t\t\ttcp_send.o tcp_stats.o\n--\nnet/rds/tcp.c=47=static LIST_HEAD(rds_tcp_tc_list);\nnet/rds/tcp.c-48-\nnet/rds/tcp.c:49:/* Track rds_tcp_connection structs so they can be cleaned up */\nnet/rds/tcp.c-50-static DEFINE_SPINLOCK(rds_tcp_conn_lock);\n--\nnet/rds/tcp.c=64=static struct ctl_table rds_tcp_sysctl_table[] = {\n--\nnet/rds/tcp.c-84-\nnet/rds/tcp.c:85:u32 rds_tcp_write_seq(struct rds_tcp_connection *tc)\nnet/rds/tcp.c-86-{\n--\nnet/rds/tcp.c-90-\nnet/rds/tcp.c:91:u32 rds_tcp_snd_una(struct rds_tcp_connection *tc)\nnet/rds/tcp.c-92-{\n--\nnet/rds/tcp.c=96=void rds_tcp_restore_callbacks(struct socket *sock,\nnet/rds/tcp.c:97:\t\t\t       struct rds_tcp_connection *tc)\nnet/rds/tcp.c-98-{\n--\nnet/rds/tcp.c=126=void rds_tcp_reset_callbacks(struct socket *sock,\n--\nnet/rds/tcp.c-128-{\nnet/rds/tcp.c:129:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp.c-130-\tstruct socket *osock = tc-\u003et_sock;\n--\nnet/rds/tcp.c=181=void rds_tcp_set_callbacks(struct socket *sock, struct rds_conn_path *cp)\nnet/rds/tcp.c-182-{\nnet/rds/tcp.c:183:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp.c-184-\n--\nnet/rds/tcp.c=219=static void rds_tcp_tc_info(struct socket *rds_sock, unsigned int len,\n--\nnet/rds/tcp.c-224-\tstruct rds_info_tcp_socket tsinfo;\nnet/rds/tcp.c:225:\tstruct rds_tcp_connection *tc;\nnet/rds/tcp.c-226-\tunsigned int copied = 0;\n--\nnet/rds/tcp.c=284=static void rds6_tcp_tc_info(struct socket *sock, unsigned int len,\n--\nnet/rds/tcp.c-289-\tstruct rds6_info_tcp_socket tsinfo6;\nnet/rds/tcp.c:290:\tstruct rds_tcp_connection *tc;\nnet/rds/tcp.c-291-\tunsigned int copied = 0;\n--\nnet/rds/tcp.c=380=static void rds_tcp_conn_free(void *arg)\nnet/rds/tcp.c-381-{\nnet/rds/tcp.c:382:\tstruct rds_tcp_connection *tc = arg;\nnet/rds/tcp.c-383-\tunsigned long flags;\n--\nnet/rds/tcp.c=395=static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)\nnet/rds/tcp.c-396-{\nnet/rds/tcp.c:397:\tstruct rds_tcp_connection *tc;\nnet/rds/tcp.c-398-\tint i, j;\n--\nnet/rds/tcp.c=437=static bool list_has_conn(struct list_head *list, struct rds_connection *conn)\nnet/rds/tcp.c-438-{\nnet/rds/tcp.c:439:\tstruct rds_tcp_connection *tc, *_tc;\nnet/rds/tcp.c-440-\n--\nnet/rds/tcp.c=458=static void rds_tcp_destroy_conns(void)\nnet/rds/tcp.c-459-{\nnet/rds/tcp.c:460:\tstruct rds_tcp_connection *tc, *_tc;\nnet/rds/tcp.c-461-\tLIST_HEAD(tmp_list);\n--\nnet/rds/tcp.c=629=static void rds_tcp_kill_sock(struct net *net)\nnet/rds/tcp.c-630-{\nnet/rds/tcp.c:631:\tstruct rds_tcp_connection *tc, *_tc;\nnet/rds/tcp.c-632-\tLIST_HEAD(tmp_list);\n--\nnet/rds/tcp.c=694=static void rds_tcp_sysctl_reset(struct net *net)\nnet/rds/tcp.c-695-{\nnet/rds/tcp.c:696:\tstruct rds_tcp_connection *tc, *_tc;\nnet/rds/tcp.c-697-\n--\nnet/rds/tcp.c=767=static int __init rds_tcp_init(void)\n--\nnet/rds/tcp.c-770-\nnet/rds/tcp.c:771:\trds_tcp_conn_slab = KMEM_CACHE(rds_tcp_connection, 0);\nnet/rds/tcp.c-772-\tif (!rds_tcp_conn_slab) {\n--\nnet/rds/tcp.h=22=struct rds_tcp_incoming {\n--\nnet/rds/tcp.h-26-\nnet/rds/tcp.h:27:struct rds_tcp_connection {\nnet/rds/tcp.h-28-\n--\nnet/rds/tcp.h=63=struct rds_tcp_statistics {\n--\nnet/rds/tcp.h-66-\tuint64_t\ts_tcp_sndbuf_full;\nnet/rds/tcp.h:67:\tuint64_t\ts_tcp_connect_raced;\nnet/rds/tcp.h-68-\tuint64_t\ts_tcp_listen_closed_stale;\n--\nnet/rds/tcp.h=76=void rds_tcp_restore_callbacks(struct socket *sock,\nnet/rds/tcp.h:77:\t\t\t       struct rds_tcp_connection *tc);\nnet/rds/tcp.h:78:u32 rds_tcp_write_seq(struct rds_tcp_connection *tc);\nnet/rds/tcp.h:79:u32 rds_tcp_snd_una(struct rds_tcp_connection *tc);\nnet/rds/tcp.h-80-extern struct rds_transport rds_tcp_transport;\n--\nnet/rds/tcp.h=82=int rds_tcp_laddr_check(struct net *net, const struct in6_addr *addr,\nnet/rds/tcp.h-83-\t\t\t__u32 scope_id);\nnet/rds/tcp.h:84:/* tcp_connect.c */\nnet/rds/tcp.h-85-int rds_tcp_conn_path_connect(struct rds_conn_path *cp);\n--\nnet/rds/tcp_connect.c=40=void rds_tcp_state_change(struct sock *sk)\n--\nnet/rds/tcp_connect.c-43-\tstruct rds_conn_path *cp;\nnet/rds/tcp_connect.c:44:\tstruct rds_tcp_connection *tc;\nnet/rds/tcp_connect.c-45-\n--\nnet/rds/tcp_connect.c=98=int rds_tcp_conn_path_connect(struct rds_conn_path *cp)\n--\nnet/rds/tcp_connect.c-109-\tstruct rds_connection *conn = cp-\u003ecp_conn;\nnet/rds/tcp_connect.c:110:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp_connect.c-111-\n--\nnet/rds/tcp_connect.c=233=void rds_tcp_conn_path_shutdown(struct rds_conn_path *cp)\nnet/rds/tcp_connect.c-234-{\nnet/rds/tcp_connect.c:235:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp_connect.c-236-\tstruct socket *sock = tc-\u003et_sock;\n--\nnet/rds/tcp_listen.c=60=rds_tcp_get_peer_sport(struct socket *sock)\n--\nnet/rds/tcp_listen.c-75- */\nnet/rds/tcp_listen.c:76:static struct rds_tcp_connection *\nnet/rds/tcp_listen.c-77-rds_tcp_accept_one_path(struct rds_connection *conn, struct socket *sock)\n--\nnet/rds/tcp_listen.c=108=void rds_tcp_conn_slots_available(struct rds_connection *conn, bool fan_out)\nnet/rds/tcp_listen.c-109-{\nnet/rds/tcp_listen.c:110:\tstruct rds_tcp_connection *tc;\nnet/rds/tcp_listen.c-111-\tstruct rds_tcp_net *rtn;\n--\nnet/rds/tcp_listen.c=152=int rds_tcp_accept_one(struct rds_tcp_net *rtn)\n--\nnet/rds/tcp_listen.c-158-\tstruct inet_sock *inet;\nnet/rds/tcp_listen.c:159:\tstruct rds_tcp_connection *rs_tcp = NULL;\nnet/rds/tcp_listen.c-160-\tint conn_state;\n--\nnet/rds/tcp_recv.c=155=static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,\n--\nnet/rds/tcp_recv.c-159-\tstruct rds_conn_path *cp = arg-\u003econn_path;\nnet/rds/tcp_recv.c:160:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp_recv.c-161-\tstruct rds_tcp_incoming *tinc = tc-\u003et_tinc;\n--\nnet/rds/tcp_recv.c=263=static int rds_tcp_read_sock(struct rds_conn_path *cp, gfp_t gfp)\nnet/rds/tcp_recv.c-264-{\nnet/rds/tcp_recv.c:265:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp_recv.c-266-\tstruct socket *sock = tc-\u003et_sock;\n--\nnet/rds/tcp_recv.c=295=int rds_tcp_recv_path(struct rds_conn_path *cp)\nnet/rds/tcp_recv.c-296-{\nnet/rds/tcp_recv.c:297:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp_recv.c-298-\tstruct socket *sock = tc-\u003et_sock;\n--\nnet/rds/tcp_recv.c=311=void rds_tcp_data_ready(struct sock *sk)\n--\nnet/rds/tcp_recv.c-314-\tstruct rds_conn_path *cp;\nnet/rds/tcp_recv.c:315:\tstruct rds_tcp_connection *tc;\nnet/rds/tcp_recv.c-316-\n--\nnet/rds/tcp_send.c=41=void rds_tcp_xmit_path_prepare(struct rds_conn_path *cp)\nnet/rds/tcp_send.c-42-{\nnet/rds/tcp_send.c:43:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp_send.c-44-\n--\nnet/rds/tcp_send.c=48=void rds_tcp_xmit_path_complete(struct rds_conn_path *cp)\nnet/rds/tcp_send.c-49-{\nnet/rds/tcp_send.c:50:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp_send.c-51-\n--\nnet/rds/tcp_send.c=70=int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,\n--\nnet/rds/tcp_send.c-73-\tstruct rds_conn_path *cp = rm-\u003em_inc.i_conn_path;\nnet/rds/tcp_send.c:74:\tstruct rds_tcp_connection *tc = cp-\u003ecp_transport_data;\nnet/rds/tcp_send.c-75-\tstruct msghdr msg = {};\n--\nnet/rds/tcp_send.c=179=void rds_tcp_write_space(struct sock *sk)\n--\nnet/rds/tcp_send.c-182-\tstruct rds_conn_path *cp;\nnet/rds/tcp_send.c:183:\tstruct rds_tcp_connection *tc;\nnet/rds/tcp_send.c-184-\n--\nnet/rds/tcp_stats.c=43=static const char * const rds_tcp_stat_names[] = {\n--\nnet/rds/tcp_stats.c-46-\t\"tcp_sndbuf_full\",\nnet/rds/tcp_stats.c:47:\t\"tcp_connect_raced\",\nnet/rds/tcp_stats.c-48-\t\"tcp_listen_closed_stale\",\n--\nsamples/landlock/sandboxer.c=313=static int add_quiet_access(const char *const env_var,\n--\nsamples/landlock/sandboxer.c-342-\t\t\t\tLANDLOCK_ACCESS_NET_BIND_TCP;\nsamples/landlock/sandboxer.c:343:\t\telse if (strcmp(str_access, \"tcp_connect\") == 0)\nsamples/landlock/sandboxer.c-344-\t\t\truleset_attr-\u003equiet_access_net |=\n--\nsamples/landlock/sandboxer.c=379=static const char help[] =\n--\nsamples/landlock/sandboxer.c-413-\t\"  - \\\"tcp_bind\\\" to quiet tcp bind denials\\n\"\nsamples/landlock/sandboxer.c:414:\t\"  - \\\"tcp_connect\\\" to quiet tcp connect denials\\n\"\nsamples/landlock/sandboxer.c-415-\t\"  - \\\"udp_bind\\\" to quiet udp bind denials\\n\"\n--\ntools/testing/selftests/bpf/progs/test_sk_storage_tracing.c=71=int BPF_PROG(trace_inet_csk_listen_start, struct sock *sk)\n--\ntools/testing/selftests/bpf/progs/test_sk_storage_tracing.c-77-\ntools/testing/selftests/bpf/progs/test_sk_storage_tracing.c:78:SEC(\"fentry/tcp_connect\")\ntools/testing/selftests/bpf/progs/test_sk_storage_tracing.c:79:int BPF_PROG(trace_tcp_connect, struct sock *sk)\ntools/testing/selftests/bpf/progs/test_sk_storage_tracing.c-80-{\n--\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c=89=static int tcp_listen(void)\n--\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c-107-\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c:108:static void tcp_connect(int listener, uint32_t flowlabel,\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c-109-\t\t\tint *client, int *accepted)\n--\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c=450=TEST_F(flowlabel, remote_flag)\n--\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c-462-\tlistener = tcp_listen();\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c:463:\ttcp_connect(listener, 7, \u0026cfd, \u0026afd);\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c-464-\n--\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c=492=TEST_F(flowlabel, reflect_flag)\n--\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c-520-\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c:521:\ttcp_connect(listener, 8, \u0026cfd, \u0026afd);\ntools/testing/selftests/net/ipv6_flowlabel_mgr.c-522-\n--\ntools/testing/selftests/net/mptcp/.gitignore-1-# SPDX-License-Identifier: GPL-2.0-only\ntools/testing/selftests/net/mptcp/.gitignore:2:mptcp_connect\ntools/testing/selftests/net/mptcp/.gitignore-3-mptcp_diag\n--\ntools/testing/selftests/net/mptcp/Makefile=8=TEST_PROGS := \\\ntools/testing/selftests/net/mptcp/Makefile-9-\tdiag.sh \\\ntools/testing/selftests/net/mptcp/Makefile:10:\tmptcp_connect.sh \\\ntools/testing/selftests/net/mptcp/Makefile:11:\tmptcp_connect_checksum.sh \\\ntools/testing/selftests/net/mptcp/Makefile:12:\tmptcp_connect_mmap.sh \\\ntools/testing/selftests/net/mptcp/Makefile:13:\tmptcp_connect_sendfile.sh \\\ntools/testing/selftests/net/mptcp/Makefile:14:\tmptcp_connect_splice.sh \\\ntools/testing/selftests/net/mptcp/Makefile-15-\tmptcp_join.sh \\\n--\ntools/testing/selftests/net/mptcp/Makefile=22=TEST_GEN_FILES := \\\ntools/testing/selftests/net/mptcp/Makefile:23:\tmptcp_connect \\\ntools/testing/selftests/net/mptcp/Makefile-24-\tmptcp_diag \\\n--\ntools/testing/selftests/net/mptcp/diag.sh=16=flush_pids()\ntools/testing/selftests/net/mptcp/diag.sh-17-{\ntools/testing/selftests/net/mptcp/diag.sh:18:\t# mptcp_connect in join mode will sleep a bit before completing,\ntools/testing/selftests/net/mptcp/diag.sh-19-\t# give it some time\n--\ntools/testing/selftests/net/mptcp/diag.sh=355=echo \"a\" | \\\n--\ntools/testing/selftests/net/mptcp/diag.sh-357-\t\tip netns exec $ns \\\ntools/testing/selftests/net/mptcp/diag.sh:358:\t\t\t./mptcp_connect -p 10000 -l -t ${timeout_poll} -w 20 \\\ntools/testing/selftests/net/mptcp/diag.sh-359-\t\t\t\t0.0.0.0 \u003e/dev/null \u0026\n--\ntools/testing/selftests/net/mptcp/diag.sh=364=echo \"b\" | \\\n--\ntools/testing/selftests/net/mptcp/diag.sh-366-\t\tip netns exec $ns \\\ntools/testing/selftests/net/mptcp/diag.sh:367:\t\t\t./mptcp_connect -p 10000 -r 0 -t ${timeout_poll} -w 20 \\\ntools/testing/selftests/net/mptcp/diag.sh-368-\t\t\t\t127.0.0.1 \u003e/dev/null \u0026\n--\ntools/testing/selftests/net/mptcp/diag.sh=384=echo \"a\" | \\\n--\ntools/testing/selftests/net/mptcp/diag.sh-386-\t\tip netns exec $ns \\\ntools/testing/selftests/net/mptcp/diag.sh:387:\t\t\t./mptcp_connect -p 10001 -l -s TCP -t ${timeout_poll} -w 20 \\\ntools/testing/selftests/net/mptcp/diag.sh-388-\t\t\t\t0.0.0.0 \u003e/dev/null \u0026\n\n"
}

gemini-3.1-pro-preview

null

null

							input: 24966
							output: 28
							thoughts: 956
						

**Analyzing the Implications of the Patch**

Okay, so `tcp_connect` is exported, that's the starting point. My focus should be on `tcp_connect`, `tcp_make_synack`, and `tcp_v4_syn_recv_sock`. Let's clarify `tcp_v6_syn_recv_sock` since it's static and shouldn't be exported, which aligns with my understanding. Oh, but `tcp_v4_syn_recv_sock` is exported, interesting. Now, let's confirm the static nature of `tcp_connect_init` again, good. And the status of `ip_dst_mtu_configured` and `ip6_dst_mtu_configured`, they are static inline as expected. What about `ipv4_default_advmss` and `ip6_default_advmss`? They are static, got it.

Time to look at the config options. The modifications are in `net/ipv4/route.c` and `net/ipv6/route.c`, which is core IPv4 and IPv6 routing. I'll need `CONFIG_INET` for IPv4 and `CONFIG_IPV6` for IPv6. Since it's core networking, there shouldn't be any unusual config dependencies beyond the standard ones required for IPv4/IPv6 support.

Now, let's re-examine the patch itself. I see that `ip_dst_mtu_configured` and `ip6_dst_mtu_configured` are static inline functions. They're called from `ipv4_default_advmss` and `ip6_default_advmss`, which are assigned to `dst_ops->default_advmss`. `dst_metric_advmss` calls `dst->ops->default_advmss(dst)`. These are then called from `tcp_connect_init`, `tcp_advertise_mss`, `tcp_make_synack`, `tcp_v4_syn_recv_sock`, and `tcp_v6_syn_recv_sock`. This reinforces my initial assessment that `tcp_connect`, `tcp_make_synack`, and `tcp_v4_syn_recv_sock` are the key functions to follow. Just confirming `tcp_v4_syn_recv_sock` is exported... and yes.

no matches

{
  "Expression": "EXPORT_SYMBOL.*tcp_v4_syn_recv_sock"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 26470
							output: 24
							thoughts: 31
						

Okay, here's my take on those thoughts, tailored for an expert audience:

**Investigating a Potentially Hidden Symbol**

Hmm, this is interesting. I'm looking at a function that isn't explicitly exported with `EXPORT_SYMBOL`, which usually means it's intended for internal use within the module or kernel it's defined in. However, the fact that it's *not* declared as `static` is raising a flag. If it weren't `static`, but also *not* exported, how is it intended to be used?

My first instinct is to see how this function, whatever it is, is being called. Specifically, I'm going to jump straight to examining `tcp_make_synack`. It's a common area for unexpected interactions. That's a good place to start, as its name suggests it would construct a SYN-ACK packet, and that makes it a prime suspect for an unexpected call. I'm betting that'll yield some insights.

no matches

{
  "Expression": "EXPORT_SYMBOL.*tcp_make_synack"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 26751
							output: 21
							thoughts: 22
						

Here's my summary, as though I were thinking through the problem:

**Digging into a Non-Exported Symbol**

Okay, so this symbol isn't exported with `EXPORT_SYMBOL`, which immediately piques my interest. That likely means it's intended for internal kernel use, not direct module access. But it's *also* not `static`, so it's technically visible within the compilation unit, which offers some clues about its scope. Time to dig deeper, starting with a crucial function – let's check `tcp_connect`. That's often a good starting point for understanding network connection establishment and where this non-exported symbol might fit in. I'm guessing that this symbol relates to TCP socket connection within the kernel. Let's see if my hunch holds up.

{
  "Expression": "EXPORT_SYMBOL.*tcp_connect"
}

{
  "Output": "net/ipv4/tcp_output.c=4298=int tcp_connect(struct sock *sk)\n--\nnet/ipv4/tcp_output.c-4403-}\nnet/ipv4/tcp_output.c:4404:EXPORT_SYMBOL(tcp_connect);\nnet/ipv4/tcp_output.c-4405-\n"
}

gemini-3.1-pro-preview

null

null

							input: 27062
							output: 24
							thoughts: 21
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**TCP Connection Function Exploration**

Okay, so I see that `tcp_connect` is definitely exported and available for use. That's as expected. Now, I need to consider IPv6 compatibility and what the equivalent function is. The question is, does the system leverage a separate, explicitly IPv6-specific function like `tcp_v6_connect`, or is this functionality handled within `tcp_connect`? It's likely I'll have to investigate further to determine how this is done and if this is a platform-specific consideration. This is a common pattern, and the nuances of the implementation will guide what I can do from here.

no matches

{
  "Expression": "EXPORT_SYMBOL.*tcp_v6_connect"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 27274
							output: 24
							thoughts: 11
						

Okay, here's my interpretation of that thought process, tailored for an expert audience, and presented as if it were my own internal monologue:

**Considering `tcp_v4_connect`**

Alright, let's see... what's on the table now? We're addressing some networking issue, probably related to establishing connections, and my mind immediately jumps to `tcp_v4_connect`. It's a fundamental function, right? A core building block for any TCP/IP-based application. This implies the current challenge likely boils down to *how* a connection is being attempted, or perhaps issues surrounding *when* and *where*. Are there problems related to the socket creation, the initial handshake, or even the subsequent data flow once a connection is established?

Knowing the context of the issue, what specifically is tripping the function up? Could there be a problem with the arguments being passed? The destination address family (AF_INET), the protocol type (SOCK_STREAM)? Perhaps an issue with the local port binding on the client side, or even firewall configurations? Is it the *system call* itself, or something it depends upon, that’s failing? I need to analyze this further. `tcp_v4_connect` is a classic case study of protocol operation and connection establishment in a TCP/IP network, a function that warrants close examination if a connection is not successfully established.

no matches

{
  "Expression": "EXPORT_SYMBOL.*tcp_v4_connect"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 27614
							output: 27
							thoughts: 59
						

Okay, let me think this through.

**Analyzing the `tcp_v4_syn_recv_sock` Symbol**

Alright, the core issue is whether `tcp_v4_syn_recv_sock` is a static function or not. It's crucial for my understanding of how this code operates. The key takeaway is: if it's *not* static, then it'll have its own specific, unique symbol address. That's good; it means I can trace it more readily.

So, the next logical step is to pinpoint its declaration. I need to verify its location, and make sure it's in the usual place. I'm going to quickly cross-reference its definition within `net/ipv4/tcp_ipv4.c`. I expect to find it there, but I need to make sure. That's the most common location, but I'm not going to assume anything. Checking it is the best step to do at this point.

{
  "Expression": "struct sock \\*tcp_v4_syn_recv_sock"
}

{
  "Output": "include/net/tcp.h=560=void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);\ninclude/net/tcp.h:561:struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,\ninclude/net/tcp.h-562-\t\t\t\t  struct request_sock *req,\n--\nnet/ipv4/tcp_ipv4.c=1655=int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)\n--\nnet/ipv4/tcp_ipv4.c-1673- */\nnet/ipv4/tcp_ipv4.c:1674:struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,\nnet/ipv4/tcp_ipv4.c-1675-\t\t\t\t  struct request_sock *req,\n"
}

gemini-3.1-pro-preview

null

null

							input: 28156
							output: 23
							thoughts: 122
						

**Analyzing `dst_metric_advmss` Usage**

Okay, so I'm confirming that we're talking about the right function here. Now, I need to see *where* this `dst_metric_advmss` is being used in the system, to understand its full context. Let's do a quick scan. Ah, good, the code search turns up a few interesting calls. `cxgbi_sock_select_mss` in the CXGBI SCSI driver, `tcp_openreq_init_rwin` in the TCP initialization, and `xfrm_default_advmss` within the IPsec framework. That gives me a much better picture. Right, next I'll focus on `tcp_openreq_init_rwin`, to see how this function is integrated.

{
  "Expression": "tcp_openreq_init_rwin"
}

{
  "Output": "include/net/tcp.h=1823=static inline bool tcp_epollin_ready(const struct sock *sk, int target)\n--\ninclude/net/tcp.h-1834-\ninclude/net/tcp.h:1835:extern void tcp_openreq_init_rwin(struct request_sock *req,\ninclude/net/tcp.h-1836-\t\t\t\t  const struct sock *sk_listener,\n--\nnet/ipv4/tcp_input.c=7620=int tcp_conn_request(struct request_sock_ops *rsk_ops,\n--\nnet/ipv4/tcp_input.c-7759-\ttcp_rsk(req)-\u003esyn_tos = TCP_SKB_CB(skb)-\u003eip_dsfield;\nnet/ipv4/tcp_input.c:7760:\ttcp_openreq_init_rwin(req, sk, dst);\nnet/ipv4/tcp_input.c-7761-\tsk_rx_queue_set(req_to_sk(req), skb);\n--\nnet/ipv4/tcp_minisocks.c=412=void tcp_twsk_purge(struct list_head *net_exit_list)\n--\nnet/ipv4/tcp_minisocks.c-430- */\nnet/ipv4/tcp_minisocks.c:431:void tcp_openreq_init_rwin(struct request_sock *req,\nnet/ipv4/tcp_minisocks.c-432-\t\t\t   const struct sock *sk_listener,\n"
}

gemini-3.1-pro-preview

null

null

							input: 28870
							output: 19
							thoughts: 37
						

Okay, here's my take on those thoughts, framed as an expert's inner monologue:

**Focusing on TCP Connection Initiation**

Alright, let's zoom in. It's clear that `tcp_openreq_init_rwin` is directly invoked by `tcp_conn_request`. That's a strong indicator. `tcp_conn_request` itself seems to be the crucial entry point, the real heart of the connection initiation process. It's the right place to put our attention, to dissect the orchestration of events and understand how everything is set up to receive data. This suggests that the receive window initialization is done right at the beginning of a connection setup, before much else is handled, which makes logical sense, in terms of resource preparation. Understanding that sequence of operations and how the `rwin` is handled here will tell us a lot about the overall connection strategy. We need to follow the execution path closely from this point.

{
  "Expression": "tcp_conn_request"
}

{
  "Output": "include/net/tcp.h=2467=int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);\ninclude/net/tcp.h:2468:int tcp_conn_request(struct request_sock_ops *rsk_ops,\ninclude/net/tcp.h-2469-\t\t     const struct tcp_request_sock_ops *af_ops,\n--\nnet/ipv4/tcp_fastopen.c=326=static struct sock *tcp_fastopen_create_child(struct sock *sk,\n--\nnet/ipv4/tcp_fastopen.c-380-\ttp-\u003ercv_mwnd_seq = tp-\u003ercv_wup + tp-\u003ercv_wnd;\nnet/ipv4/tcp_fastopen.c:381:\t/* tcp_conn_request() is sending the SYNACK,\nnet/ipv4/tcp_fastopen.c-382-\t * and queues the child into listener accept queue.\n--\nnet/ipv4/tcp_input.c=7594=u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,\n--\nnet/ipv4/tcp_input.c-7619-\nnet/ipv4/tcp_input.c:7620:int tcp_conn_request(struct request_sock_ops *rsk_ops,\nnet/ipv4/tcp_input.c-7621-\t\t     const struct tcp_request_sock_ops *af_ops,\n--\nnet/ipv4/tcp_ipv4.c=1655=int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)\n--\nnet/ipv4/tcp_ipv4.c-1660-\nnet/ipv4/tcp_ipv4.c:1661:\treturn tcp_conn_request(\u0026tcp_request_sock_ops,\nnet/ipv4/tcp_ipv4.c-1662-\t\t\t\t\u0026tcp_request_sock_ipv4_ops, sk, skb);\n--\nnet/ipv6/tcp_ipv6.c=1316=static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)\n--\nnet/ipv6/tcp_ipv6.c-1328-\nnet/ipv6/tcp_ipv6.c:1329:\treturn tcp_conn_request(\u0026tcp6_request_sock_ops,\nnet/ipv6/tcp_ipv6.c-1330-\t\t\t\t\u0026tcp_request_sock_ipv6_ops, sk, skb);\n--\nnet/mptcp/subflow.c=669=static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)\n--\nnet/mptcp/subflow.c-678-\nnet/mptcp/subflow.c:679:\treturn tcp_conn_request(\u0026mptcp_subflow_v4_request_sock_ops,\nnet/mptcp/subflow.c-680-\t\t\t\t\u0026subflow_request_sock_ipv4_ops,\n--\nnet/mptcp/subflow.c=700=static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)\n--\nnet/mptcp/subflow.c-716-\nnet/mptcp/subflow.c:717:\treturn tcp_conn_request(\u0026mptcp_subflow_v6_request_sock_ops,\nnet/mptcp/subflow.c-718-\t\t\t\t\u0026subflow_request_sock_ipv6_ops, sk, skb);\n"
}

gemini-3.1-pro-preview

null

null

							input: 30044
							output: 23
							thoughts: 93
						

**Analyzing TCP Connection Establishment**

Okay, so I'm thinking about where to start digging into the TCP connection process. `tcp_conn_request` immediately jumps out. It's the point where the incoming SYN packets are processed, and it handles the initial request socket setup, including calculating the Maximum Segment Size. That sounds like a pretty critical function.

Therefore, the functions I really want to focus on are: `tcp_connect`, which initiates the connection, then, of course,  `tcp_conn_request` itself, which seems key to the server-side, then `tcp_make_synack` as it seems to be important, and lastly `tcp_v4_syn_recv_sock` - that's a key function in handling the SYN/ACK, isn't it?

Right, the next step is to make sure `tcp_conn_request` is exported. Need to confirm that before I move forward.

no matches

{
  "Expression": "EXPORT_SYMBOL.*tcp_conn_request"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 30373
							output: 18
							thoughts: 271
						

**Analyzing the Implications of this Patch**

Okay, so this isn't a simple static variable we're dealing with; it's more dynamic than that, which is good to keep in mind. Let's dig in and see how this works. I'll take a look at `tcp_v4_conn_request` and `tcp_v6_conn_request` to get a better handle on things. Right, `tcp_v4_conn_request` isn't static, but `tcp_v6_conn_request` is. So, we have a list of potentially relevant functions to examine further: `tcp_connect`, `tcp_conn_request`, `tcp_make_synack`, and `tcp_v4_syn_recv_sock`.

Now, I need to see if this change has any wider ripple effects. Are `ip_dst_mtu_configured` or `ip6_dst_mtu_configured` used *anywhere* else? No, it looks like this patch is isolated to modifying `ipv4_default_advmss` and `ip6_default_advmss`, which is helpful.

Now, let's look at the config options. The patch modifies `net/ipv4/route.c` and `net/ipv6/route.c`. So, if `CONFIG_INET` and `CONFIG_IPV6` are enabled, these files are compiled. We already know that `CONFIG_INET` is always enabled in Linux networking, and `CONFIG_IPV6` seems like a pretty safe bet to include. Let me check and make sure that `IPV6` is actually needed.

{
  "Expression": "config IPV6"
}

{
  "Output": "net/ipv6/Kconfig-5-\nnet/ipv6/Kconfig:6:menuconfig IPV6\nnet/ipv6/Kconfig-7-\tbool \"The IPv6 protocol\"\n--\nnet/ipv6/Kconfig=19=if IPV6\nnet/ipv6/Kconfig-20-\nnet/ipv6/Kconfig:21:config IPV6_ROUTER_PREF\nnet/ipv6/Kconfig-22-\tbool \"IPv6: Router Preference (RFC 4191) support\"\n--\nnet/ipv6/Kconfig-30-\nnet/ipv6/Kconfig:31:config IPV6_ROUTE_INFO\nnet/ipv6/Kconfig-32-\tbool \"IPv6: Route Information (RFC 4191) support\"\n--\nnet/ipv6/Kconfig-38-\nnet/ipv6/Kconfig:39:config IPV6_OPTIMISTIC_DAD\nnet/ipv6/Kconfig-40-\tbool \"IPv6: Enable RFC 4429 Optimistic DAD\"\n--\nnet/ipv6/Kconfig=102=config INET6_IPCOMP\n--\nnet/ipv6/Kconfig-111-\nnet/ipv6/Kconfig:112:config IPV6_MIP6\nnet/ipv6/Kconfig-113-\ttristate \"IPv6: Mobility\"\n--\nnet/ipv6/Kconfig-119-\nnet/ipv6/Kconfig:120:config IPV6_ILA\nnet/ipv6/Kconfig-121-\ttristate \"IPv6: Identifier Locator Addressing (ILA)\"\n--\nnet/ipv6/Kconfig=146=config INET6_TUNNEL\n--\nnet/ipv6/Kconfig-149-\nnet/ipv6/Kconfig:150:config IPV6_VTI\nnet/ipv6/Kconfig-151-\ttristate \"Virtual (secure) IPv6: tunneling\"\n--\nnet/ipv6/Kconfig-161-\nnet/ipv6/Kconfig:162:config IPV6_SIT\nnet/ipv6/Kconfig-163-\ttristate \"IPv6: IPv6-in-IPv4 tunnel (SIT driver)\"\n--\nnet/ipv6/Kconfig-176-\nnet/ipv6/Kconfig:177:config IPV6_SIT_6RD\nnet/ipv6/Kconfig-178-\tbool \"IPv6: IPv6 Rapid Deployment (6RD)\"\n--\nnet/ipv6/Kconfig-195-\nnet/ipv6/Kconfig:196:config IPV6_NDISC_NODETYPE\nnet/ipv6/Kconfig-197-\tbool\nnet/ipv6/Kconfig-198-\nnet/ipv6/Kconfig:199:config IPV6_TUNNEL\nnet/ipv6/Kconfig-200-\ttristate \"IPv6: IP-in-IPv6 tunnel (RFC2473)\"\n--\nnet/ipv6/Kconfig-209-\nnet/ipv6/Kconfig:210:config IPV6_GRE\nnet/ipv6/Kconfig-211-\ttristate \"IPv6: GRE tunnel\"\n--\nnet/ipv6/Kconfig-227-\nnet/ipv6/Kconfig:228:config IPV6_FOU\nnet/ipv6/Kconfig-229-\ttristate\n--\nnet/ipv6/Kconfig-231-\nnet/ipv6/Kconfig:232:config IPV6_FOU_TUNNEL\nnet/ipv6/Kconfig-233-\ttristate\n--\nnet/ipv6/Kconfig-236-\nnet/ipv6/Kconfig:237:config IPV6_MULTIPLE_TABLES\nnet/ipv6/Kconfig-238-\tbool \"IPv6: Multiple Routing Tables\"\n--\nnet/ipv6/Kconfig-242-\nnet/ipv6/Kconfig:243:config IPV6_SUBTREES\nnet/ipv6/Kconfig-244-\tbool \"IPv6: source address based routing\"\n--\nnet/ipv6/Kconfig-256-\nnet/ipv6/Kconfig:257:config IPV6_MROUTE\nnet/ipv6/Kconfig-258-\tbool \"IPv6: multicast routing\"\n--\nnet/ipv6/Kconfig-264-\nnet/ipv6/Kconfig:265:config IPV6_MROUTE_MULTIPLE_TABLES\nnet/ipv6/Kconfig-266-\tbool \"IPv6: multicast policy routing\"\n--\nnet/ipv6/Kconfig-278-\nnet/ipv6/Kconfig:279:config IPV6_PIMSM_V2\nnet/ipv6/Kconfig-280-\tbool \"IPv6: PIM-SM version 2 support\"\n--\nnet/ipv6/Kconfig-285-\nnet/ipv6/Kconfig:286:config IPV6_SEG6_LWTUNNEL\nnet/ipv6/Kconfig-287-\tbool \"IPv6: Segment Routing Header encapsulation support\"\n--\nnet/ipv6/Kconfig-299-\nnet/ipv6/Kconfig:300:config IPV6_SEG6_HMAC\nnet/ipv6/Kconfig-301-\tbool \"IPv6: Segment Routing HMAC support\"\n--\nnet/ipv6/Kconfig-311-\nnet/ipv6/Kconfig:312:config IPV6_SEG6_BPF\nnet/ipv6/Kconfig-313-\tdef_bool y\n--\nnet/ipv6/Kconfig-316-\nnet/ipv6/Kconfig:317:config IPV6_RPL_LWTUNNEL\nnet/ipv6/Kconfig-318-\tbool \"IPv6: RPL Source Routing Header support\"\n--\nnet/ipv6/Kconfig-327-\nnet/ipv6/Kconfig:328:config IPV6_IOAM6_LWTUNNEL\nnet/ipv6/Kconfig-329-\tbool \"IPv6: IOAM Pre-allocated Trace insertion support\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 32557
							output: 167
							thoughts: 492
						

**My Analysis of the TCP MSS Patch**

Okay, here's the breakdown. This patch is interesting because it's fundamentally altering how we calculate and advertise the TCP Maximum Segment Size (MSS) in both IPv4 and IPv6. It's essentially introducing `ip_dst_mtu_configured` and `ip6_dst_mtu_configured` to bypass ICMP-derived Path MTU (PMTU) and instead use the configured route or device MTU. This change directly impacts the MSS values sent during the connection setup process – the SYN and SYN-ACK packets. Given its core networking nature and the potential functional shift in MSS determination, this is definitely something worth fuzzing.

My primary focus will be on these functions, given the patch's scope:

*   `tcp_connect`
*   `tcp_conn_request`
*   `tcp_make_synack`
*   `tcp_v4_syn_recv_sock`

I've confirmed that the `IPV6` config is the relevant one here. I also double-checked and verified that the patch touches `net/ipv4/route.c` and `net/ipv6/route.c`, which makes sense. There aren't any other crucial configs needed for this analysis.

I've also validated that `tcp_conn_request` is indeed a good place to start. It's used for both IPv4 and IPv6 via the `tcp_v4_conn_request` and `tcp_v6_conn_request` functions, and crucially, it calls `tcp_openreq_init_rwin`, which in turn calls `dst_metric_advmss`. This is a direct entry point for manipulating the MSS calculation, making it a prime candidate.

As for the remaining functions, `tcp_v4_syn_recv_sock` is used for IPv4, and also for IPv4-mapped IPv6 addresses, so that seems ok. `tcp_v6_syn_recv_sock` is there for IPv6, but is static, which is worth considering. The other functions `tcp_make_synack` and `tcp_connect` also have versions that are called for both IPv4 and IPv6 respectively.

Given this analysis, my function list is solid. I'm ready to proceed. Now, I will call `set-results`.

{
  "EnableConfigs": [
    "IPV6"
  ],
  "FocusSymbols": [
    "tcp_connect",
    "tcp_conn_request",
    "tcp_make_synack",
    "tcp_v4_syn_recv_sock"
  ],
  "Reasoning": "The patch modifies the calculation of the advertised TCP MSS in IPv4 and IPv6. It introduces `ip_dst_mtu_configured` and `ip6_dst_mtu_configured` to ignore ICMP-learned path MTU and instead use the configured route or device MTU. This affects the TCP MSS advertised during connection setup (SYN/SYN-ACK). The changes are in core networking and functionally alter how MSS is determined, which is worth fuzzing.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "IPV6"
  ],
  "FocusSymbols": [
    "tcp_connect",
    "tcp_conn_request",
    "tcp_make_synack",
    "tcp_v4_syn_recv_sock"
  ],
  "Reasoning": "The patch modifies the calculation of the advertised TCP MSS in IPv4 and IPv6. It introduces `ip_dst_mtu_configured` and `ip6_dst_mtu_configured` to ignore ICMP-learned path MTU and instead use the configured route or device MTU. This affects the TCP MSS advertised during connection setup (SYN/SYN-ACK). The changes are in core networking and functionally alter how MSS is determined, which is worth fuzzing.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

best-expensive

null

{
  "KMSANReasoning": "The patch modifies the calculation of the advertised TCP MSS by introducing `ip_dst_mtu_configured()` and `ip6_dst_mtu_configured()`. These functions read existing, initialized fields from routing and device structures (`dst_entry`, `rt6_info`, `fib6_info`, `net_device`, `inet6_dev`) to determine the configured MTU, ignoring ICMP-learned path MTU. There are no new allocations, no new structures passed to user space, and no changes that would expose uninitialized memory. Any potential issues introduced by this patch, such as NULL pointer dereferences or out-of-bounds accesses, would be caught by standard KASAN or other standard bug detectors. Therefore, a dedicated KMSAN fuzzing session is not required.",
  "NeedsKMSAN": false
}

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.

For your convenience, here is the diff of the changes:
commit c8d674b98c859c7f3a62c1cc4f7be9830dc85318
Author: syz-cluster <triage@syzkaller.com>
Date:   Fri Aug 14 07:33:13 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/net/ip.h b/include/net/ip.h
index 7f2fe1a8401b1..a8f57b4f4aa23 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -506,6 +506,31 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
 	return res;
 }
 
+/* Configured/administrative MTU of a route, for advertising the TCP MSS.
+ *
+ * Unlike ip_dst_mtu_maybe_forward(), this deliberately ignores the
+ * ICMP-learned path MTU (rt->rt_pmtu).  The advertised MSS bounds what the
+ * peer may send to us and must reflect our receive capability (the device or
+ * route-configured MTU), not a path MTU learned on the reverse (send)
+ * direction, which may not apply to the peer->us path and outlives the fnhe
+ * for the whole connection.  See RFC 2923 section 2.3 and the comment above
+ * tcp_advertise_mss().
+ */
+static inline unsigned int ip_dst_mtu_configured(const struct dst_entry *dst)
+{
+	unsigned int mtu, res;
+
+	rcu_read_lock();
+	mtu = dst_metric_raw(dst, RTAX_MTU);
+	if (!mtu)
+		mtu = READ_ONCE(dst_dev_rcu(dst)->mtu);
+	mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
+	res = mtu - lwtunnel_headroom(dst->lwtstate, mtu);
+	rcu_read_unlock();
+
+	return res;
+}
+
 static inline unsigned int ip_skb_dst_mtu(struct sock *sk,
 					  const struct sk_buff *skb)
 {
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 09ffe0f13ce75..ac1acc0b74368 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -385,6 +385,43 @@ static inline unsigned int ip6_dst_mtu_maybe_forward(const struct dst_entry *dst
 	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
 }
 
+/* Configured/administrative MTU of a route, for advertising the TCP MSS.
+ *
+ * Unlike ip6_dst_mtu_maybe_forward(), this ignores any ICMPv6-learned path
+ * MTU (which is kept on the RTF_CACHE exception route) and returns the MTU of
+ * the underlying route (fib6_pmtu) or the egress device.  The advertised MSS
+ * bounds what the peer may send to us and must reflect our receive
+ * capability, not a path MTU learned on the reverse (send) direction.  See
+ * RFC 2923 section 2.3 and the comment above tcp_advertise_mss().
+ */
+static inline unsigned int ip6_dst_mtu_configured(const struct dst_entry *dst)
+{
+	const struct rt6_info *rt = dst_rt6_info(dst);
+	const struct fib6_info *from;
+	struct inet6_dev *idev;
+	unsigned int mtu = 0;
+
+	rcu_read_lock();
+	/* IPv6 keeps the learned PMTU and the configured MTU in the same
+	 * RTAX_MTU slot: the learned value sits on this (possibly RTF_CACHE)
+	 * dst, the configured one on the underlying route.  Reach the latter
+	 * via ->from (fib6_pmtu), populated by ip6_route_info_create().
+	 */
+	from = rcu_dereference(rt->from);
+	if (from)
+		mtu = from->fib6_pmtu;
+	if (!mtu) {
+		mtu = IPV6_MIN_MTU;
+		idev = __in6_dev_get(dst_dev_rcu(dst));
+		if (idev)
+			mtu = max_t(unsigned int, mtu, READ_ONCE(idev->cnf.mtu6));
+	}
+	rcu_read_unlock();
+
+	mtu = min_t(unsigned int, mtu, IP6_MAX_MTU);
+	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
+}
+
 u32 ip6_mtu_from_fib6(const struct fib6_result *res,
 		      const struct in6_addr *daddr,
 		      const struct in6_addr *saddr);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index fd688e1f879f5..46aa98c921833 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1334,8 +1334,8 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
 
 	rcu_read_lock();
 	net = dst_dev_net_rcu(dst);
-	advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
-				   net->ipv4.ip_rt_min_advmss);
+	advmss = max_t(unsigned int, ip_dst_mtu_configured(dst) - header_size,
+		       net->ipv4.ip_rt_min_advmss);
 	rcu_read_unlock();
 
 	return min(advmss, IPV4_MAX_PMTU - header_size);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 5968ce5ad1508..e2056bd0df3c4 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3261,7 +3261,7 @@ void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk)
 
 static unsigned int ip6_default_advmss(const struct dst_entry *dst)
 {
-	unsigned int mtu = dst6_mtu(dst);
+	unsigned int mtu = ip6_dst_mtu_configured(dst);
 	struct net *net;
 
 	mtu -= sizeof(struct ipv6hdr) + sizeof(struct tcphdr);

gemini-3.1-pro-preview

null

null

							input: 3468
							output: 190
							thoughts: 612
						

**My Assessment of the Patch's Uninitialized Memory Risks**

Okay, so this patch is switching things up with how we calculate the advertised TCP MSS, specifically by using these new `ip_dst_mtu_configured()` and `ip6_dst_mtu_configured()` functions in `ipv4_default_advmss()` and `ip6_default_advmss()`. The whole point is to ignore path MTU learned via ICMP, which makes sense in the context of tuning TCP behavior.

Let's break down the data flow. For IPv4, the patch now grabs the MTU from `dst_metric_raw(dst, RTAX_MTU)` and `dst_dev_rcu(dst)->mtu`. For IPv6, it's pulling from `rt->from->fib6_pmtu` and `idev->cnf.mtu6`. It's pretty straightforward: these values are being used to compute `advmss`.

My initial thought is, does this introduce any uninitialized memory vulnerabilities? After looking into it, I can see that the patch doesn't involve any new memory allocations. It's just modifying how we *read* the MTU information from existing, already initialized structures within the network stack. Specifically we're reading `dst_entry`, `rt6_info`, `fib6_info`, `inet6_dev` fields to get the values from. I'm pretty confident there's no way this exposes uninitialized memory to a user space application.

The variables being read are standard fields within their respective structs; `dst->metrics`, `net_device->mtu`, `fib6_info`, and `inet6_dev` and are all primitive types. Standard checks like KASAN and LOCKDEP will be enough to catch any bugs in the logic change if they were introduced. KMSAN is great for uninitialized memory issues, but it's not applicable here.

To be extra certain, I just went through the fields. `dst_metric_raw` accesses `dst->metrics`. `dst_dev_rcu(dst)->mtu` reads from `net_device->mtu`. `rt->from` dereferences a `fib6_info` pointer. `from->fib6_pmtu` is a `u32`. `idev->cnf.mtu6` is an `s32`. All of these are initialized fields, so no, there are no uninitialized memory risks.

In short, my reasoning is that this patch changes MTU calculation, reading existing and initialized fields from `dst_entry`, `rt6_info`, `fib6_info`, `net_device` and `inet6_dev` for IPv4 and IPv6 to determine the configured MTU. It doesn't introduce any new allocations, structures sent to user space, or otherwise expose any uninitialized memory. Standard bug detectors will handle any problems that might arise from the patch. No KMSAN is necessary.

{
  "KMSANReasoning": "The patch modifies the calculation of the advertised TCP MSS by introducing `ip_dst_mtu_configured()` and `ip6_dst_mtu_configured()`. These functions read existing, initialized fields from routing and device structures (`dst_entry`, `rt6_info`, `fib6_info`, `net_device`, `inet6_dev`) to determine the configured MTU, ignoring ICMP-learned path MTU. There are no new allocations, no new structures passed to user space, and no changes that would expose uninitialized memory. Any potential issues introduced by this patch, such as NULL pointer dereferences or out-of-bounds accesses, would be caught by standard KASAN or other standard bug detectors. Therefore, a dedicated KMSAN fuzzing session is not required.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch modifies the calculation of the advertised TCP MSS by introducing `ip_dst_mtu_configured()` and `ip6_dst_mtu_configured()`. These functions read existing, initialized fields from routing and device structures (`dst_entry`, `rt6_info`, `fib6_info`, `net_device`, `inet6_dev`) to determine the configured MTU, ignoring ICMP-learned path MTU. There are no new allocations, no new structures passed to user space, and no changes that would expose uninitialized memory. Any potential issues introduced by this patch, such as NULL pointer dereferences or out-of-bounds accesses, would be caught by standard KASAN or other standard bug detectors. Therefore, a dedicated KMSAN fuzzing session is not required.",
  "NeedsKMSAN": false
}