Wind River Support Network

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.