From: Eric Dumazet edumazet@google.com
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
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[ 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@google.com Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- 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 54f0e7fcd0e2..199b54e75359 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -361,7 +361,7 @@ static unsigned int __bpf_prog_run(void *ctx, 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); @@ -380,7 +380,7 @@ static unsigned int __bpf_prog_run(void *ctx, 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);