bpf: zero extend the result of an arena 32-bit cmpxchg
In the Linux kernel, the following vulnerability has been resolved: bpf: zero extend the result of an arena 32-bit cmpxchg bpf_convert_ctx_accesses() rewrites an atomic on an arena pointer from BPF_STX | BPF_ATOMIC to BPF_STX | BPF_PROBE_ATOMIC, and it runs before bpf_opt_subreg_zext_lo32_rnd_hi32(). That pass emits an explicit zero extension for a 32-bit cmpxchg even when bpf_jit_needs_zext() is false. This is done because on some architectures 32-bit cmpxchg requires explicit zero extension for the dst register. E.g. on x86-64 'lock cmpxchg' does not change the %eax if comparison is successful, while BPF semantics declare that each operation on a 32-bit register zero extends it's upper half. is_cmpxchg_insn() matches BPF_MODE == BPF_ATOMIC only, so an arena cmpxchg misses said zero extension adjustment. This patch adjusts is_cmpxchg_insn() to match BPF_PROBE_ATOMIC alongside BPF_ATOMIC.
CVE-2026-98049
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-2026-98049
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": "d503a04f8bc0c75dc9db9452d8cc79d748afb752",
"lessThan": "1bb1be18263995b159cf5afad3a05500ba6d2a7b",
"versionType": "git"
},
{
"status": "affected",
"version": "d503a04f8bc0c75dc9db9452d8cc79d748afb752",
"lessThan": "6bb6ae5ab1beffda51dabf41612f501d07f10fc6",
"versionType": "git"
},
{
"status": "affected",
"version": "d503a04f8bc0c75dc9db9452d8cc79d748afb752",
"lessThan": "1c1b476d43a8b6c9bc04600369dd8cc39950d98e",
"versionType": "git"
},
{
"status": "affected",
"version": "d503a04f8bc0c75dc9db9452d8cc79d748afb752",
"lessThan": "4814ed6406f3493bd554ad046da5f7fc04833571",
"versionType": "git"
}
],
"programFiles": [
"kernel/bpf/fixups.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.10"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.10",
"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/fixups.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98049
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #48839 · Revision 1
- Added to Heist Feed
- Publisher date