bpf: Fix out-of-bounds read of rtt_min in sock_ops

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98643
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-18 16:17:17 UTC
Updated2026-10-19 10:19:28 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Fix out-of-bounds read of rtt_min in sock_ops A sockops prog reading skops->rtt_min never checks the sk type: on the tcp_conn_request() path sock_ops->sk is a request_sock (non-full), and the ctx rewrite casts it to a tcp_sock (full) and reads rtt_min past the end of the request_sock, returning dirty adjacent memory. SEC("sockops") int prog(struct bpf_sock_ops *skops) { switch (skops->op) { case BPF_SOCK_OPS_RWND_INIT: leak = skops->rtt_min; /* reads the request_sock OOB */ ... } } For instance one such read returned rtt_min=0xffff8881, the high half of a leaked kernel pointer. Guarding that cast is exactly what SOCK_OPS_GET_FIELD() does -- it checks is_locked_tcp_sock and returns 0 when sock_ops->sk is not a locked full socket. Every other tcp_sock field in sock_ops goes through it; rtt_min is the only one open-coded, so it skips the check. Read rtt_min through SOCK_OPS_GET_FIELD() too. rtt_min is a bit special: it is a struct minmax and we only want the current min, so pass rtt_min.s[0].v. That is equivalent to the old hand-computed offset offsetof(struct tcp_sock, rtt_min) + sizeof_field(struct minmax_sample, t) (s[0] sits at rtt_min + 0 and .v at + sizeof(.t), i.e. what minmax_get() returns), so the loaded field is unchanged and only the full-sock guard is added. The two BUILD_BUG_ON()s that protected the hand-computed offset are no longer needed. Before patch: 0: r1 = *(u64 *)(r1 +0) ; r1 = skops->sk 1: r1 = *(u32 *)(r1 +2324) ; ((tcp_sock *)sk)->rtt_min.s[0].v After patch: 0: *(u64 *)(r1 +56) = r9 1: r9 = *(u8 *)(r1 +50) ; is_locked_tcp_sock 2: if r9 == 0 goto pc+4 ; not a locked full sock -> 0 3: r9 = *(u64 *)(r1 +56) 4: r1 = *(u64 *)(r1 +0) ; r1 = skops->sk 5: r1 = *(u32 *)(r1 +2324) ; rtt_min.s[0].v 6: goto pc+2 7: r9 = *(u64 *)(r1 +56) 8: r1 = 0

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 44f0e43037d3a17b043843ba67610ac7c7e37db6 0c796efa919f52f788c22c79d1f1b70321696b3d git Not specified
CNA Linux Linux affected 44f0e43037d3a17b043843ba67610ac7c7e37db6 fc9d0e6e9d86fbefe7b8fe6ee49f4cf102add79d git Not specified
CNA Linux Linux affected 44f0e43037d3a17b043843ba67610ac7c7e37db6 fd6bf2721933d8c90bc4ce57f3e204c9295e7e3f git Not specified
CNA Linux Linux affected 44f0e43037d3a17b043843ba67610ac7c7e37db6 a8a9becbac93a9f54f4d565f1f3005eb08a7912f git Not specified
CNA Linux Linux affected 44f0e43037d3a17b043843ba67610ac7c7e37db6 3a46f14e6cf375f3ca38f8f6e6524749e24ea0a8 git Not specified
CNA Linux Linux affected 44f0e43037d3a17b043843ba67610ac7c7e37db6 6785313d4fac96afb21ef193610c1fa88b1a9e64 git Not specified
CNA Linux Linux affected 44f0e43037d3a17b043843ba67610ac7c7e37db6 cba54d142c43ec96d8c4d566f66439e8c0afded7 git Not specified
CNA Linux Linux affected 44f0e43037d3a17b043843ba67610ac7c7e37db6 75f8cf22463d82bb1fb0239a3d485fc8f4c8ef03 git Not specified
CNA Linux Linux affected 4.16 Not specified
CNA Linux Linux unaffected 4.16 semver Not specified
CNA Linux Linux unaffected 5.10.271 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.222 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.189 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.158 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.112 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.55 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.9 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/75f8cf22463d82bb1fb0239a3d485fc8f4c8ef03 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fc9d0e6e9d86fbefe7b8fe6ee49f4cf102add79d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a8a9becbac93a9f54f4d565f1f3005eb08a7912f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/cba54d142c43ec96d8c4d566f66439e8c0afded7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6785313d4fac96afb21ef193610c1fa88b1a9e64 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3a46f14e6cf375f3ca38f8f6e6524749e24ea0a8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0c796efa919f52f788c22c79d1f1b70321696b3d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fd6bf2721933d8c90bc4ce57f3e204c9295e7e3f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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