bpf: Reject legacy packet loads from callbacks
Summary
| CVE | CVE-2026-98044 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-25 11:17:33 UTC |
| Updated | 2026-10-21 13:21:20 UTC |
| Description | 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. |
Risk And Classification
EPSS: 0.001660000 probability, percentile 0.055130000 (date 2026-10-21)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 8674e2db06cff6b50f2216eed9a761d15425bb34 cebda2a2bb4183550eae9dcf888c16407b4fffda git | Not specified |
| CNA | Linux | Linux | affected ce01a4e5cfac7adbe0be565f90cd32ecbb2f8337 3484a99303912db62428494a9061212049027e57 git | Not specified |
| CNA | Linux | Linux | affected ee861486e377edc55361c08dcbceab3f6b6577bd bc489c0c9b8c86bd7fac42cfd1bb152f042fca56 git | Not specified |
| CNA | Linux | Linux | affected ee861486e377edc55361c08dcbceab3f6b6577bd e7d28823c662128caae63f14e16bd394916c139b git | Not specified |
| CNA | Linux | Linux | affected 928d354ae3557e8f755a227e67be88034eb3cd7f git | Not specified |
| CNA | Linux | Linux | affected 8a800497d9f6c2ec9c2c1ba7b71d0ac2ea7f7bbe git | Not specified |
| CNA | Linux | Linux | affected de1055e7f9e67af32b1f3376066272b04e5223c0 git | Not specified |
| CNA | Linux | Linux | affected 37ad2bb11e9de92cb7b94548705eeedd87f7d392 git | Not specified |
| CNA | Linux | Linux | affected d846d83bdacbd8f14fc45c63b8c1d22608452e1c git | Not specified |
| CNA | Linux | Linux | affected 6.12.101 6.12.114 semver | Not specified |
| CNA | Linux | Linux | affected 6.18.42 6.18.53 semver | Not specified |
| CNA | Linux | Linux | affected 5.10.265 5.11 semver | Not specified |
| CNA | Linux | Linux | affected 5.15.216 5.16 semver | Not specified |
| CNA | Linux | Linux | affected 6.1.183 6.2 semver | Not specified |
| CNA | Linux | Linux | affected 6.6.148 6.7 semver | Not specified |
| CNA | Linux | Linux | affected 7.0.10 7.1 semver | Not specified |
| CNA | Linux | Linux | affected 7.1 | Not specified |
| CNA | Linux | Linux | unaffected 7.1 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.114 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.53 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2.7 7.2.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.3 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/3484a99303912db62428494a9061212049027e57 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e7d28823c662128caae63f14e16bd394916c139b | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/bc489c0c9b8c86bd7fac42cfd1bb152f042fca56 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/cebda2a2bb4183550eae9dcf888c16407b4fffda | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.