223 lines
13 KiB
JSON
223 lines
13 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-99173",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-09-25T10:25:14.399Z",
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"datePublished": "2026-10-28T10:35:28.017Z",
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"dateUpdated": "2026-10-31T12:44:40.199Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-31T12:44:40.199Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"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."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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"baseScore": 7.8,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"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."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/tracefs/event_inode.c"
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],
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"versions": [
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{
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"version": "2ef3d120d19faba3dec35b10a025b00db0284373",
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"lessThan": "5819018dc29fb2ac2fd4865d507f9893c89c0624",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8e556432477e97ad6179c61b61a32bf5f1af2355",
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"lessThan": "dd2c767814a876be0f16f0b7f98a403dc176f51e",
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"status": "affected",
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},
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{
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"lessThan": "4586ef24ce390e8becb9f3e5852d5d3978b01c33",
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"status": "affected",
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},
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{
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"version": "8e556432477e97ad6179c61b61a32bf5f1af2355",
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"lessThan": "45fcfd5d9c10e0aa977ed5b9bd445707e01bb107",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8e556432477e97ad6179c61b61a32bf5f1af2355",
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"lessThan": "2cd88c498ecff8e22bf4c397b8eb226db70ac343",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "384f383c5aa7bfd619d9f56a513a36e533428186",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "6.6.46",
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"lessThan": "6.6.161",
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"status": "affected",
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"versionType": "semver"
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},
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{
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"version": "6.10.5",
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"lessThan": "6.11",
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"status": "affected",
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"versionType": "semver"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/tracefs/event_inode.c"
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],
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"versions": [
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{
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"version": "6.11",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "6.11",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.161",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.115",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.59",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2.13",
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"lessThanOrEqual": "7.2.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.3",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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"nodes": [
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.6.46",
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"versionEndExcluding": "6.6.161"
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/5819018dc29fb2ac2fd4865d507f9893c89c0624"
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},
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{
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"url": "https://git.kernel.org/stable/c/dd2c767814a876be0f16f0b7f98a403dc176f51e"
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},
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{
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"url": "https://git.kernel.org/stable/c/4586ef24ce390e8becb9f3e5852d5d3978b01c33"
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},
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{
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"url": "https://git.kernel.org/stable/c/45fcfd5d9c10e0aa977ed5b9bd445707e01bb107"
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},
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{
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"url": "https://git.kernel.org/stable/c/2cd88c498ecff8e22bf4c397b8eb226db70ac343"
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}
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],
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"title": "eventfs: Free the eventfs_inode after an rcu grace period too",
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"x_generator": {
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