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bpf: fix 64-bit divide 

ALU64_DIV instruction should be dividing 64-bit by 64-bit,
whereas do_div() does 64-bit by 32-bit divide.
x64 and arm64 JITs correctly implement 64 by 64 unsigned divide.
llvm BPF backend emits code assuming that ALU64_DIV does 64 by 64.

Fixes: 89aa075832 ("net: sock: allow eBPF programs to be attached to sockets")
Reported-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2015-04-27 14:40:37 -07:00 committed by David S. Miller
parent 8e046d68ba
commit 876a7ae65b
1 changed files with 6 additions and 6 deletions
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12
kernel/bpf/core.c
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@ -357,8 +357,8 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
ALU64_MOD_X:
if (unlikely(SRC == 0))
return 0;
tmp = DST;
DST = do_div(tmp, SRC);
div64_u64_rem(DST, SRC, &tmp);
DST = tmp;
CONT;
ALU_MOD_X:
if (unlikely(SRC == 0))
@ -367,8 +367,8 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
DST = do_div(tmp, (u32) SRC);
CONT;
ALU64_MOD_K:
tmp = DST;
DST = do_div(tmp, IMM);
div64_u64_rem(DST, IMM, &tmp);
DST = tmp;
CONT;
ALU_MOD_K:
tmp = (u32) DST;
@ -377,7 +377,7 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
ALU64_DIV_X:
if (unlikely(SRC == 0))
return 0;
do_div(DST, SRC);
DST = div64_u64(DST, SRC);
CONT;
ALU_DIV_X:
if (unlikely(SRC == 0))
@ -387,7 +387,7 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
DST = (u32) tmp;
CONT;
ALU64_DIV_K:
do_div(DST, IMM);
DST = div64_u64(DST, IMM);
CONT;
ALU_DIV_K:
tmp = (u32) DST;