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.
Product status
dea9989a3f3961faede93752cd81eb5a9514d911 (git) before 342aa1ee995ef5bbf876096dc3a5e51218d76fa4
4c122e8ae14950cf6b59d208fc5160f7c601e746 (git) before 58bd87d0e69204dbd739e4387a1edb0c4b1644e7
e52567173ba86dbffb990595fbe60e2e83899372 (git) before d13281ae7ea8902b21d99d10a2c8caf0bdec0455
bffacdb80b93b7b5e96b26fad64cc490a6c7d6c7 (git) before c845894ebd6fb43226b3118d6b017942550910c5
7.0-rc1
Any version before 7.0-rc1
6.12.80 (semver)
6.18.21 (semver)
6.19.11 (semver)
7.0-rc5 (original_commit_for_fix)
References
git.kernel.org/...c/342aa1ee995ef5bbf876096dc3a5e51218d76fa4
git.kernel.org/...c/58bd87d0e69204dbd739e4387a1edb0c4b1644e7
git.kernel.org/...c/d13281ae7ea8902b21d99d10a2c8caf0bdec0455
git.kernel.org/...c/c845894ebd6fb43226b3118d6b017942550910c5