writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs()
In the Linux kernel, the following vulnerability has been resolved: writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() When a container exits, the following BUG_ON() is occasionally triggered: ================================================================== VFS: Busy inodes after unmount of sdb (ext4) ------------[ cut here ]------------ kernel BUG at fs/super.c:695! CPU: 3 PID: 6 Comm: containerd-shim Tainted: G OE K 6.6 #1 pstate: 63400009 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : generic_shutdown_super+0xf0/0x100 lr : generic_shutdown_super+0xf0/0x100 Call trace: generic_shutdown_super+0xf0/0x100 kill_block_super+0x20/0x48 ext4_kill_sb+0x28/0x60 deactivate_locked_super+0x54/0x130 deactivate_super+0x84/0xa0 cleanup_mnt+0xa4/0x140 __cleanup_mnt+0x18/0x28 task_work_run+0x78/0xe0 do_notify_resume+0x204/0x240 ================================================================== The root cause is a race between cgroup_writeback_umount() and inode_switch_wbs()/cleanup_offline_cgwb(). There is a window between inode_prepare_wbs_switch() returning true and the subsequent wb_queue_isw() call. Following is the process that triggers the issue: CPU A (umount) | CPU B (writeback) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ inode_switch_wbs/cleanup_offline_cgwb atomic_inc(&isw_nr_in_flight) inode_prepare_wbs_switch -> passes SB_ACTIVE check __iget(inode) generic_shutdown_super sb->s_flags &= ~SB_ACTIVE cgroup_writeback_umount
CVE-2026-64378
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-64378
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
"lessThan": "087d5b8b501c570f84bf655164e6698c3ce146e0",
"versionType": "git"
},
{
"status": "affected",
"version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
"lessThan": "3c9c9648f77e4d14e50676bc51c2174ba9c8d361",
"versionType": "git"
},
{
"status": "affected",
"version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
"lessThan": "5c3265f3252b2ee50707adaaa3f9bd0df3df72de",
"versionType": "git"
},
{
"status": "affected",
"version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
"lessThan": "c923cc3cb5cd8945ceaf08252754110643446593",
"versionType": "git"
},
{
"status": "affected",
"version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
"lessThan": "685fc15a410885b6d4dee64de0dce721b9428b12",
"versionType": "git"
},
{
"status": "affected",
"version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
"lessThan": "53eeaf4d63068dbc7708b0c7adb20151c812feca",
"versionType": "git"
},
{
"status": "affected",
"version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
"lessThan": "cba38ec4cbd3a7b8b942a8d52531a05be8a9ff0d",
"versionType": "git"
},
{
"status": "affected",
"version": "c5cbbec54fe71c4de2d34f8c0ec8fbfdd7f17339",
"versionType": "git"
},
{
"status": "affected",
"version": "4.4.5",
"lessThan": "4.5",
"versionType": "semver"
}
],
"programFiles": [
"fs/fs-writeback.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.5"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.5",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.96",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.39",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.4",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/fs-writeback.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-64378
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #41020 · Revision 1
- Added to Heist Feed
- Publisher date