bpf: Keep refcount_acquire nullable for borrowed RCU kptrs
In the Linux kernel, the following vulnerability has been resolved: bpf: Keep refcount_acquire nullable for borrowed RCU kptrs bpf_refcount_acquire() is fallible for a borrowed reference because the object may have reached a zero refcount. The verifier therefore keeps KF_RET_NULL on the return value unless the argument is an owning reference. An RCU-protected load of a local kptr is marked MEM_ALLOC, but it only receives NON_OWN_REF when the pointee contains a graph node. A refcounted object without a graph node consequently looks like an owning reference even though the loaded register has no acquired reference state. If the program drops the last real reference while remaining in the RCU critical section, refcount_inc_not_zero() returns NULL while the verifier treats the result as non-NULL. Only classify the argument as owning when it is backed by a verifier-tracked reference. This retains the non-NULL return for pointers from bpf_obj_new(), bpf_kptr_xchg(), or an earlier successful acquisition, while requiring a NULL check for borrowed RCU kptrs. [ kkd: Rewrote commit log ]
CVE-2026-98038
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-2026-98038
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": "1b12171533a9bb23cf6fba7262b479028b65e1e8",
"lessThan": "85bfc8b6db43502444c428eaa2de20bdd2fb9064",
"versionType": "git"
},
{
"status": "affected",
"version": "1b12171533a9bb23cf6fba7262b479028b65e1e8",
"lessThan": "8d19e2cdfba9ba8c8eb6a459cd666bec00a1d2c6",
"versionType": "git"
},
{
"status": "affected",
"version": "1b12171533a9bb23cf6fba7262b479028b65e1e8",
"lessThan": "85074498228a2500ea8b8039c49cc1ab8ad5328f",
"versionType": "git"
},
{
"status": "affected",
"version": "1b12171533a9bb23cf6fba7262b479028b65e1e8",
"lessThan": "dc36739e5cc9f60485418a910b42bc95339218d2",
"versionType": "git"
}
],
"programFiles": [
"kernel/bpf/verifier.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.8"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.8",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.7",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/bpf/verifier.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98038
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #48833 · Revision 1
- Added to Heist Feed
- Publisher date