CVE-2026-93148: bpf: Reject MEM_ALLOC BTF accesses past object bounds
In the Linux kernel, the following vulnerability has been resolved:
bpf: Reject MEMALLOC BTF accesses past object bounds
BTF struct walks relax the struct-size check for accesses through a trailing flexible array. That is valid for ordinary BTF type walking, but PTRTOBTFID | MEMALLOC values point to objects allocated with the static BTF type size.
When walking a MEMALLOC object, reject the access before applying the flexible-array relaxation if the access range extends past the struct size. Apply the same policy to struct ID matching so kfunc and kptr type checks do not walk past the allocated object bounds either.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Reject MEM_ALLOC BTF accesses before applying trailing flexible-array relaxation when the access range extends past the allocated object or static BTF struct size; apply the same bounds policy to struct ID matching for kfunc and kptr type checks.
Event History
Frequently Asked Questions
What access pattern is affected?
The issue affects BPF accesses through PTR_TO_BTF_ID | MEM_ALLOC values when a BTF struct walk reaches beyond the object’s static BTF type size through a trailing flexible array. The corrected behavior rejects the access before flexible-array size relaxation is applied.
Are kfunc and kptr checks covered by the fix?
Yes. The same object-bound policy is applied to struct ID matching, preventing kfunc and kptr type checks from walking beyond the bounds of the allocated MEM_ALLOC object.