blk-cgroup: fix UAF in __blkcg_rstat_flush()
In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix UAF in __blkcg_rstat_flush() When multiple blkgs in the same blkcg are released concurrently, a use-after-free can occur. The race happens when one blkg's __blkcg_rstat_flush() removes another blkg's iostat entries via llist_del_all(). The second blkg sees an empty list and proceeds to free itself while the first is still iterating over its entries. Move the flush from __blkg_release() (RCU callback) to blkg_release() (before call_rcu). This ensures the RCU grace period waits for any concurrent flush's rcu_read_lock() section to complete before freeing.
CVE-2026-63802
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-2026-63802
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": "20cb1c2fb7568a6054c55defe044311397e01ddb",
"lessThan": "96e545410c4f74c89d496c1d5d9ef8d08f14368b",
"versionType": "git"
},
{
"status": "affected",
"version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
"lessThan": "bbebd9425cad3573d1527441753899b926525a0f",
"versionType": "git"
},
{
"status": "affected",
"version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
"lessThan": "5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6",
"versionType": "git"
},
{
"status": "affected",
"version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
"lessThan": "afebe44facc48a61761e885bbb7f0380d4a603ec",
"versionType": "git"
},
{
"status": "affected",
"version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
"lessThan": "0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2",
"versionType": "git"
},
{
"status": "affected",
"version": "0f6090d90f627d8c58f939067d6c6821ce1b3c68",
"versionType": "git"
},
{
"status": "affected",
"version": "6.3.9",
"lessThan": "6.4",
"versionType": "semver"
}
],
"programFiles": [
"block/blk-cgroup.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.4"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.4",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.144",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.95",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.38",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.3",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"block/blk-cgroup.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-63802
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40832 · Revision 1
- Added to Heist Feed
- Publisher date