CVE-2026-31413 - bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR

CVE-2026-31413 - bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR

https://cvefeed.io/rssfeed/latest.atom / Sun, 04/12/2026 - 09:42
CVE ID :CVE-2026-31413
Published : April 12, 2026, 6:16 a.m. | 53 minutes ago
Description :In the Linux kernel, the following vulnerability has been resolved: bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR maybe_fork_scalars() is called for both BPF_AND and BPF_OR when the source operand is a constant. When dst has signed range [-1, 0], it forks the verifier state: the pushed path gets dst = 0, the current path gets dst = -1. For BPF_AND this is correct: 0 & K == 0. For BPF_OR this is wrong: 0 | K == K, not 0. The pushed path therefore tracks dst as 0 when the runtime value is K, producing an exploitable verifier/runtime divergence that allows out-of-bounds map access. Fix this by passing env->insn_idx (instead of env->insn_idx + 1) to push_stack(), so the pushed path re-executes the ALU instruction with dst = 0 and naturally computes the correct result for any opcode.
Severity: 0.0 | NA
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