entry: Fix seccomp bypass after ptrace with TSYNC

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Summary

CVECVE-2026-89603
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:45 UTC
Updated2026-09-11 20:19:45 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: entry: Fix seccomp bypass after ptrace with TSYNC Sashiko review pointed out the following issue. If a thread is stopped in syscall_trace_enter() for ptrace, another thread can install a seccomp filter with SECCOMP_FILTER_FLAG_TSYNC (e.g., via seccomp_attach_filter()). This will successfully set SYSCALL_WORK_SECCOMP on the stopped thread, but syscall_trace_enter() evaluates a cached 'work' variable sampled on entry. Consequently, the subsequent check for SYSCALL_WORK_SECCOMP misses the newly assigned flag, and the filter is silently bypassed. This race condition could allow an unprivileged process to execute a prohibited system call (e.g., execve) that the newly installed filter was intended to block, especially since the tracer might have modified the system call number during the ptrace stop. Fix this by re-reading the syscall_work flags after ptrace handling, so that any new SYSCALL_WORK_SECCOMP flag set by another thread via TSYNC during the ptrace stop is observed before the subsequent seccomp check.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 142781e108b13b2b0e8f035cfb5bfbbc8f14d887 459f33f82864723a7fa366cf1091d9c6c893b6b2 git Not specified
CNA Linux Linux affected 142781e108b13b2b0e8f035cfb5bfbbc8f14d887 ab4647459098a43e9d6fdb860836f08c962f3774 git Not specified
CNA Linux Linux affected 142781e108b13b2b0e8f035cfb5bfbbc8f14d887 4a3591287fb7f808e209b4974ed337f609a2006b git Not specified
CNA Linux Linux affected 5.9 Not specified
CNA Linux Linux unaffected 5.9 semver Not specified
CNA Linux Linux unaffected 6.18.51 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/459f33f82864723a7fa366cf1091d9c6c893b6b2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4a3591287fb7f808e209b4974ed337f609a2006b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ab4647459098a43e9d6fdb860836f08c962f3774 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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