tracing/user_events: Clear copied tracing state before fork duplication

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89750
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:20:05 UTC
Updated2026-09-11 20:20:05 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: tracing/user_events: Clear copied tracing state before fork duplication dup_task_struct() copies user_event_mm from the parent into the child, without grabbing a reference to it. user_event_mm_dup() should replace it, but it leaves that copied pointer unmodified if user_event_mm_alloc() fails. When the child exits, user_event_mm_remove() decrements a reference the child never owned, which ultimately frees user_event_mm, while the parent still as a stale pointer to it. This creates a UAF, which KASAN reports as: BUG: KASAN: slab-use-after-free in current_user_event_mm+0x51/0x1d0 Write of size 4 at addr ffff888005010d30 by task init/44 Call Trace: <TASK> kasan_report+0xce/0x100 kasan_check_range+0x10f/0x1e0 current_user_event_mm+0x51/0x1d0 user_events_ioctl+0x82e/0x15c0 __x64_sys_ioctl+0x139/0x1c0 do_syscall_64+0xce/0x450 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 44: __kasan_kmalloc+0x8f/0xa0 __kmalloc_cache_noprof+0x180/0x3a0 user_event_mm_alloc+0x3c/0x1f0 current_user_event_mm+0x88/0x1d0 Freed by task 42: __kasan_slab_free+0x43/0x70 kfree+0x13a/0x390 process_one_work+0x696/0xf90 worker_thread+0x420/0xba0 The fix simply clears the copied pointer before any possible failure. In case of failure, the child then has nothing to free.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 7235759084a4f8524a46bd2638885ff3b34ce279 63b39e49a4c9d68e010e96b26fc7374f0864f2b1 git Not specified
CNA Linux Linux affected 7235759084a4f8524a46bd2638885ff3b34ce279 25a0758cf6bdbfddac2be71124c9bd0692f4b0b1 git Not specified
CNA Linux Linux affected 7235759084a4f8524a46bd2638885ff3b34ce279 b799f67119aff179719a0b1e12441ebbdaaf62f9 git Not specified
CNA Linux Linux affected 7235759084a4f8524a46bd2638885ff3b34ce279 390f6bd8583d177029d9df4bea6667509e55a765 git Not specified
CNA Linux Linux affected 6.4 Not specified
CNA Linux Linux unaffected 6.4 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 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/63b39e49a4c9d68e010e96b26fc7374f0864f2b1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/25a0758cf6bdbfddac2be71124c9bd0692f4b0b1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b799f67119aff179719a0b1e12441ebbdaaf62f9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/390f6bd8583d177029d9df4bea6667509e55a765 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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