In the Linux kernel, the following vulnerability has been resolved: bpf: Don't predict JMP32...

In the Linux kernel, the following vulnerability has been resolved:

bpf: Don't predict JMP32 pointer vs zero comparisons

Consider the following program:

    r1 = map_value;      /* low 32 bits are zero at runtime */
    r6 = 0xdead000000000000;
    if w1 != 0 goto l1;
l0: r1 += r6;
    r2 = *(u64 *)(r1 + 0);
    exit;
l1: r6 = 0;
    goto l0;

At the moment is_branch_taken() reports the jump as always taken, because it does not distinguish between BPF_JMP and BPF_JMP32 comparisons when processing 'if w1 != 0 ...'.