bpf: handle jset (if a & b ...) as a jump in CFG computation

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: bpf: handle jset (if a & b ...) as a jump in CFG computation BPF_JSET is a conditional jump and currently verifier.c:can_jump() does not know about that. This can lead to incorrect live registers and SCC computation. E.g. in the following example: 1: r0 = 1; 2: r2 = 2; 3: if r1 & 0x7 goto +1; 4: exit; 5: r0 = r2; 6: exit; W/o this fix insn_successors(3) will return only (4), a jump to (5) would be missed and r2 won't be marked as alive at (3).

References

• https://git.kernel.org/stable/c/65eb166b8636365ad3d6e36d50a7c5edfe6cc66e
• https://git.kernel.org/stable/c/261b30ad1516f4b9edd500aa6e8d6315c8fc109a
• https://git.kernel.org/stable/c/3157f7e2999616ac91f4d559a8566214f74000a5