bpf: don't downgrade half-dead scalar zero spills to STACK_ZERO
In the Linux kernel, the following vulnerability has been resolved: bpf: don't downgrade half-dead scalar zero spills to STACK_ZERO states.c:__clean_func_state() can downgrade scalar zero spill to STACK_ZERO in the following case: *(u64 *)(r10 - 8) = 0; ... checkpoint ... r1 = *(u32 *)(r10 - 4); ... no reads from r10-8 ... Here 4 bytes at r10-8 are dead and verifier changes scalar spill to a combination: 0000pppp (p stands for poison). Such a change breaks precision propagation chains. All places that produce STACK_ZERO should call bpf_mark_chain_precision() for the zero source. This patch fixes the bug in a simplest way possible: avoids converting stack spills of zero to STACK_ZERO. Two smarter approaches are possible: - do bpf_mark_chain_precision() from __clean_func_state() - check slot liveness information in check_stack_write_fixed_off() I investigated both and the changes required are a bit tricky, hence go with a simple fix for the time being.
CVE-2026-98132
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-2026-98132
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": "be23266b4a08540aa43d8503a2ea10247c8daebe",
"lessThan": "436fa689630b741a77ef8c4a6f426479affd5bac",
"versionType": "git"
},
{
"status": "affected",
"version": "be23266b4a08540aa43d8503a2ea10247c8daebe",
"lessThan": "2f3536bff8823d3c5fdbbe15e17bfca696cc2b2e",
"versionType": "git"
}
],
"programFiles": [
"kernel/bpf/states.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.1",
"versionType": "semver"
},
{
"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/states.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98132
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #38226 · Revision 1
- Added to Heist Feed
- Publisher date