bpf: Reject legacy packet loads from callbacks
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject legacy packet loads from callbacks check_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a subprogram as an implicit return with R0 set to zero. It calls prepare_func_exit() to explore this synthesized path. When the load is reached directly from a synchronous callback, prepare_func_exit() enforces the callback return contract and marks R0 precise. R0 is not derived from a real instruction on this path, so precision backtracking reaches the callback call with R0 still requested and triggers the "callback unexpected regs" verifier bug. A privileged program loader can therefore cause a verifier warning and an -EFAULT BPF_PROG_LOAD. These legacy packet-load instructions are deprecated. Reject them from callbacks rather than complicating their implicit-return model. Check all active frames before constructing the implicit return so nested static subprograms cannot hide the callback context. Global functions are verified independently with a fresh frame zero, so an active-frame check cannot identify a global function called from a callback. Also check the complete subprogram call graph during stack-depth validation and reject a function containing a legacy load when any caller is a callback. This covers global and static descendants without making has_ld_abs transitive, preserving its per-function BTF return-type check. Ordinary uses outside callbacks remain supported.
CVE-2026-98044
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-2026-98044
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": "8674e2db06cff6b50f2216eed9a761d15425bb34",
"lessThan": "cebda2a2bb4183550eae9dcf888c16407b4fffda",
"versionType": "git"
},
{
"status": "affected",
"version": "ce01a4e5cfac7adbe0be565f90cd32ecbb2f8337",
"lessThan": "3484a99303912db62428494a9061212049027e57",
"versionType": "git"
},
{
"status": "affected",
"version": "ee861486e377edc55361c08dcbceab3f6b6577bd",
"lessThan": "bc489c0c9b8c86bd7fac42cfd1bb152f042fca56",
"versionType": "git"
},
{
"status": "affected",
"version": "ee861486e377edc55361c08dcbceab3f6b6577bd",
"lessThan": "e7d28823c662128caae63f14e16bd394916c139b",
"versionType": "git"
},
{
"status": "affected",
"version": "928d354ae3557e8f755a227e67be88034eb3cd7f",
"versionType": "git"
},
{
"status": "affected",
"version": "8a800497d9f6c2ec9c2c1ba7b71d0ac2ea7f7bbe",
"versionType": "git"
},
{
"status": "affected",
"version": "de1055e7f9e67af32b1f3376066272b04e5223c0",
"versionType": "git"
},
{
"status": "affected",
"version": "37ad2bb11e9de92cb7b94548705eeedd87f7d392",
"versionType": "git"
},
{
"status": "affected",
"version": "d846d83bdacbd8f14fc45c63b8c1d22608452e1c",
"versionType": "git"
},
{
"status": "affected",
"version": "6.12.101",
"lessThan": "6.12.114",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.18.42",
"lessThan": "6.18.53",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.10.265",
"lessThan": "5.11",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.15.216",
"lessThan": "5.16",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.1.183",
"lessThan": "6.2",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.6.148",
"lessThan": "6.7",
"versionType": "semver"
},
{
"status": "affected",
"version": "7.0.10",
"lessThan": "7.1",
"versionType": "semver"
}
],
"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": "7.1"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.1",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.53",
"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-2026-98044
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #48836 · Revision 1
- Added to Heist Feed
- Publisher date