fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()
In the Linux kernel, the following vulnerability has been resolved: fs/resctrl: Prevent use-after-free in rdtgroup_kn_put() A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that need the structure to remain valid across a sleep (while waiting on acquiring rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with rdtgroup_kn_put(). The release path is intended to serve as the fallback freer: if the count drops to zero and the group has already been marked RDT_DELETED, rdtgroup_kn_put() frees the structure. The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting from a resctrl directory remove or resctrl fs unmount act as the primary freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter. These two freers race. rdtgroup_kn_put() commits waitcount == 0 with atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags. Between those two operations a concurrent caller of free_all_child_rdtgrp() or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via atomic_read(), call rdtgroup_remove(), and kfree() the structure. The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then a use-after-free, and the structure may even be freed twice if the freed memory happens to satisfy the RDT_DELETED flag check. Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so that the decrem
CVE-2026-93100
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-2026-93100
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": "b8511ccc75c033f6d54188ea4df7bf1e85778740",
"lessThan": "971b40e3ca1279ca4917889e0195d33b66d071a4",
"versionType": "git"
},
{
"status": "affected",
"version": "b8511ccc75c033f6d54188ea4df7bf1e85778740",
"lessThan": "828ff461c136b95d13b8d712c0a7a06a640e313a",
"versionType": "git"
},
{
"status": "affected",
"version": "b8511ccc75c033f6d54188ea4df7bf1e85778740",
"lessThan": "ae69f936e8ffed553d899ba4c02f8a7461a89e54",
"versionType": "git"
},
{
"status": "affected",
"version": "b8511ccc75c033f6d54188ea4df7bf1e85778740",
"lessThan": "4c593c62c1499665baebbb41b70e2c9b7e947b86",
"versionType": "git"
},
{
"status": "affected",
"version": "b8511ccc75c033f6d54188ea4df7bf1e85778740",
"lessThan": "f5bcf539484d2d604c2f2330e09487ea090b21c7",
"versionType": "git"
},
{
"status": "affected",
"version": "d20edc0bca5577bab38acb5b190619c922ddebf8",
"versionType": "git"
},
{
"status": "affected",
"version": "1b006f8cbde9f3dabdfafe2ff7aa9f831ed5b625",
"versionType": "git"
},
{
"status": "affected",
"version": "40300f986e47dbc8f1d02e5080385f5cf9f85f70",
"versionType": "git"
},
{
"status": "affected",
"version": "b5a4949897ebada8132d54c93208989482503103",
"versionType": "git"
},
{
"status": "affected",
"version": "4.14.170",
"lessThan": "4.15",
"versionType": "semver"
},
{
"status": "affected",
"version": "4.19.102",
"lessThan": "4.20",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.4.18",
"lessThan": "5.5",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.5.2",
"lessThan": "5.6",
"versionType": "semver"
}
],
"programFiles": [
"fs/resctrl/rdtgroup.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.6"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.6",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.52",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/resctrl/rdtgroup.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-93100
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #48709 · Revision 1
- Added to Heist Feed
- Publisher date