CVE-2026-98041: bpf: Don't predict JMP32 pointer vs zero comparisons
bpf: Don't predict JMP32 pointer vs zero comparisons
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.113-1Fixed in 7.2.12-1Fixed in 7.2.13-1 - Upgrade
Upgrade
debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.113-1~deb12u1
Event History
Frequently Asked Questions
What condition is required to trigger the verifier error?
The BPF program must use a JMP32 comparison between a pointer-derived value and zero, where the low 32 bits can be zero at runtime. The verifier incorrectly treats the branch as always taken because it does not distinguish JMP32 from full-width BPF_JMP comparisons.
What is the practical consequence of the incorrect branch prediction?
It can cause the verifier to reason about an unreachable branch incorrectly. In the provided example, this allows control-flow reasoning to miss the path where a pointer-derived register is combined with a nonzero 64-bit value before a memory load.
How can I determine whether a BPF program may be affected?
Review BPF programs accepted by the kernel for 32-bit conditional jumps, such as comparisons using w-register operands, involving pointer-derived values and zero. Programs using only full-width comparisons or without this control-flow pattern are not described by the supplied data as affected.