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bpf: fix divides by zero

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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: bd4cf0ed33 ("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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet 2018-01-30 03:37:44 +01:00 • committed by Greg Kroah-Hartman
parent 96d9b2338b
commit b72ba2a0d8
1 changed files with 2 additions and 2 deletions
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4
kernel/bpf/core.c
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@ -444,7 +444,7 @@ 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);
@ -463,7 +463,7 @@ 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);