Message ID | 1515807803.3606.7.camel@gmail.com |
---|---|
State | Accepted, archived |
Delegated to: | BPF Maintainers |
Headers | show |
Series | [v2] bpf: fix divides by zero | expand |
On Fri, Jan 12, 2018 at 05:43:23PM -0800, Eric Dumazet wrote: > From: Eric Dumazet <edumazet@google.com> > > Divides by zero are not nice, lets avoid them if possible. > > Also do_div() seems not needed when dealing with 32bit operands, > but this seems a minor detail. > > Fixes: bd4cf0ed331a ("net: filter: rework/optimize internal BPF interpreter's instruction set") > Signed-off-by: Eric Dumazet <edumazet@google.com> > Reported-by: syzbot <syzkaller@googlegroups.com> > --- Applied, Thank you Eric.
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 51ec2dda7f08c6c90af084589bb6d80662c77d12..7949e8b8f94e9cc196e0449214493ccce61b0903 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -956,7 +956,7 @@ static unsigned int ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, DST = tmp; CONT; ALU_MOD_X: - if (unlikely(SRC == 0)) + if (unlikely((u32)SRC == 0)) return 0; tmp = (u32) DST; DST = do_div(tmp, (u32) SRC); @@ -975,7 +975,7 @@ static unsigned int ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, DST = div64_u64(DST, SRC); CONT; ALU_DIV_X: - if (unlikely(SRC == 0)) + if (unlikely((u32)SRC == 0)) return 0; tmp = (u32) DST; do_div(tmp, (u32) SRC);