{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99173","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.399Z","datePublished":"2026-10-28T10:35:28.017Z","dateUpdated":"2026-10-31T12:44:40.199Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-31T12:44:40.199Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\neventfs: Free the eventfs_inode after an rcu grace period too\n\ntracefs_d_revalidate() reads ->is_freed of the eventfs_inode that\ndentry->d_fsdata points to, and ->d_revalidate() is called in rcu\npathwalk mode with nothing but rcu_read_lock() held. The dentry itself\nstays around for such a walker, but tracefs_d_release() drops its\nreference to the eventfs_inode when the dentry is killed, and\nrelease_ei() then frees it after a grace period of eventfs_srcu. An\nSRCU grace period doesn't wait for rcu_read_lock() sections, so the\nwalker can read an eventfs_inode that is already gone.\n\nWith a pathwalk held up in tracefs_d_revalidate() while the dentry goes\naway:\n\n  BUG: KASAN: slab-use-after-free in tracefs_d_revalidate+0x76/0x90\n  Read of size 1 at addr ff1100010152d8d0 by task walker/97\n  Call Trace:\n   <TASK>\n   tracefs_d_revalidate+0x76/0x90\n   lookup_fast+0x320/0x640\n   path_lookupat+0x160/0xb00\n   filename_lookup+0x1f1/0x5b0\n   vfs_statx+0xd7/0x3b0\n   vfs_fstatat+0x4d/0x90\n   __do_sys_newfstatat+0xa0/0x100\n   do_syscall_64+0x10e/0x5e0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  [...]\n  Allocated by task 1:\n   __kmalloc_cache_noprof+0x249/0x560\n   eventfs_create_dir+0x7a/0x590\n   event_create_dir+0x2fb/0xcf0\n   trace_add_event_call+0xbf/0x150\n  [...]\n  Freed by task 11:\n   kfree+0x1db/0x5b0\n   srcu_invoke_callbacks+0x3a3/0x620\n   process_one_work+0x937/0x1810\n   worker_thread+0x4f1/0xd60\n\nBefore commit 8e556432477e (\"eventfs: Use SRCU for freeing\neventfs_inodes\") release_ei() used call_rcu(), which covered the walker,\nwhile eventfs_iterate() needs the SRCU grace period. Wait for both and\nchain call_rcu() from the SRCU callback."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - A local newfstatat() pathwalk reaches lookup_fast()->tracefs_d_revalidate(); concurrent invalidation invokes tracefs_d_release()->eventfs_d_release()->put_ei()->release_ei(), the patched free path. No network or device input reaches this tracefs race.\nAC:L - The attacker can create a nonpersistent user event, instantiate its dentry, then unregister and close it while concurrent threads loop newfstatat(). This controls event teardown, dentry invalidation, and the RCU walk, making the race repeatable.\nPR:L - user_event_capable() requires CAP_PERFMON only for USER_EVENT_REG_PERSIST; ordinary DIAG_IOCSREG and DIAG_IOCSUNREG have no capable() check. A low-privilege user with delegated DAC access to user_events_data can create and auto-delete the required eventfs directory.\nUI:N - The same process registers the event, stats events/user_events/<name>, and unregisters or closes it to trigger auto-deletion; no victim action is required.\nS:U - The dangling d_fsdata access in tracefs_d_revalidate() and the release_ei() free both occur within the host kernel. Resulting privilege escalation does not cross a VM, IOMMU, or other security authority.\nC:H - After free_ei_rcu() frees the eventfs_inode, dentry->d_fsdata remains a dangling pointer read by tracefs_d_revalidate(). Repeated event creation permits slab grooming and attacker-influenced reuse, giving the disclosure potential of a kernel UAF.\nI:H - release_ei() permits an RCU walker to retain a pointer into a freed kmalloc object that the attacker can churn through eventfs_create_dir(). Reclaiming the object provides the heap-spraying and control-flow corruption potential of an exploitable kernel UAF.\nA:H - The reported KASAN trace demonstrates a slab-use-after-free read in tracefs_d_revalidate() after free_ei_rcu() calls kfree(). Repeatedly racing event deletion with pathwalk can therefore cause a kernel oops or panic."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/tracefs/event_inode.c"],"versions":[{"version":"2ef3d120d19faba3dec35b10a025b00db0284373","lessThan":"5819018dc29fb2ac2fd4865d507f9893c89c0624","status":"affected","versionType":"git"},{"version":"8e556432477e97ad6179c61b61a32bf5f1af2355","lessThan":"dd2c767814a876be0f16f0b7f98a403dc176f51e","status":"affected","versionType":"git"},{"version":"8e556432477e97ad6179c61b61a32bf5f1af2355","lessThan":"4586ef24ce390e8becb9f3e5852d5d3978b01c33","status":"affected","versionType":"git"},{"version":"8e556432477e97ad6179c61b61a32bf5f1af2355","lessThan":"45fcfd5d9c10e0aa977ed5b9bd445707e01bb107","status":"affected","versionType":"git"},{"version":"8e556432477e97ad6179c61b61a32bf5f1af2355","lessThan":"2cd88c498ecff8e22bf4c397b8eb226db70ac343","status":"affected","versionType":"git"},{"version":"384f383c5aa7bfd619d9f56a513a36e533428186","status":"affected","versionType":"git"},{"version":"6.6.46","lessThan":"6.6.161","status":"affected","versionType":"semver"},{"version":"6.10.5","lessThan":"6.11","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/tracefs/event_inode.c"],"versions":[{"version":"6.11","status":"affected"},{"version":"0","lessThan":"6.11","status":"unaffected","versionType":"semver"},{"version":"6.6.161","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.115","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.59","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.13","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.46","versionEndExcluding":"6.6.161"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.18.59"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10.5"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/5819018dc29fb2ac2fd4865d507f9893c89c0624"},{"url":"https://git.kernel.org/stable/c/dd2c767814a876be0f16f0b7f98a403dc176f51e"},{"url":"https://git.kernel.org/stable/c/4586ef24ce390e8becb9f3e5852d5d3978b01c33"},{"url":"https://git.kernel.org/stable/c/45fcfd5d9c10e0aa977ed5b9bd445707e01bb107"},{"url":"https://git.kernel.org/stable/c/2cd88c498ecff8e22bf4c397b8eb226db70ac343"}],"title":"eventfs: Free the eventfs_inode after an rcu grace period too","x_generator":{"engine":"bippy-1.2.0"}}}}