From 6eca013bef784aaf7be1a6262e3fe2de75476166 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 29 Jan 2018 00:36:44 +0100 Subject: bpf: fix divides by zero [ upstream commit c366287ebd698ef5e3de300d90cd62ee9ee7373e ] 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 Reported-by: syzbot Signed-off-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index aaa44244d498..2246115365d9 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -949,7 +949,7 @@ select_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); @@ -968,7 +968,7 @@ select_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); -- cgit v1.2.3