From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ 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 <edumazet@xxxxxxxxxx>
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
kernel/bpf/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index aaa4424..2246115 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -949,7 +949,7 @@ 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);
@@ -968,7 +968,7 @@ 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);
--
2.9.5