nfsd: defer vfree of compound ops to fix rpc_status UAF
In the Linux kernel, the following vulnerability has been resolved: nfsd: defer vfree of compound ops to fix rpc_status UAF The rpc_status netlink dumpit walks every in-flight svc_rqst under rcu_read_lock and, for NFSv4 requests, reads opnums out of args->ops[]. But args->ops is a separate vmalloc buffer freed synchronously by vfree() in nfsd4_release_compoundargs() at the end of every compound. The dumpit's rcu_read_lock pins the svc_rqst struct itself (freed via kfree_rcu), but nothing defers the vfree of the ops buffer across the RCU grace period. A concurrent compound completion can therefore free the buffer while the dumpit is reading it — a use-after-free on vmalloc memory. The trailing seqcount recheck (smp_load_acquire of rq_status_counter) cannot undo a load that already retired against freed memory. Fix by replacing vfree(args->ops) with kvfree_rcu_mightsleep(), which defers the free until after an RCU grace period. This makes the existing rcu_read_lock in the dumpit sufficient to protect the read. The tradeoff is that completed compound ops buffers (up to 200 * sizeof(struct nfsd4_op)) persist in memory slightly longer, across one grace period, before being reclaimed.
CVE-2026-89690
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-2026-89690
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": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
"lessThan": "48f72aff24f7a7329209dc6cbc27c869f3e3595c",
"versionType": "git"
},
{
"status": "affected",
"version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
"lessThan": "6703199f4d7e7f37d6a726a849eb358e8fae72fb",
"versionType": "git"
},
{
"status": "affected",
"version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
"lessThan": "19413ccc45070a7270b9e25c2a258daf7f91de42",
"versionType": "git"
},
{
"status": "affected",
"version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
"lessThan": "fca26a3fc19ed02278aa2a150af82d43db0302cb",
"versionType": "git"
}
],
"programFiles": [
"fs/nfsd/nfs4xdr.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.7"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.7",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/nfsd/nfs4xdr.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89690
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #35175 · Revision 1
- Added to Heist Feed
- Publisher date