diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2018-01-29 02:49:00 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-31 12:55:57 +0100 |
| commit | 265d7657c9baf09d57eb386d0374e912e9649626 (patch) | |
| tree | 1f946e259824241ecee5a0137457a87dc3cc0435 /kernel/bpf | |
| parent | 4606077802f2c6ef7aff5185d9f7d99a50784ffd (diff) | |
bpf: fix 32-bit divide by zero
[ upstream commit 68fda450a7df51cff9e5a4d4a4d9d0d5f2589153 ]
due to some JITs doing if (src_reg == 0) check in 64-bit mode
for div/mod operations mask upper 32-bits of src register
before doing the check
Fixes: 622582786c9e ("net: filter: x86: internal BPF JIT")
Fixes: 7a12b5031c6b ("sparc64: Add eBPF JIT.")
Reported-by: syzbot+48340bb518e88849e2e3@syzkaller.appspotmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8e0bf890ffb7..5c56ff9eeed2 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3391,6 +3391,24 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) for (i = 0; i < insn_cnt; i++, insn++) { + if (insn->code == (BPF_ALU | BPF_MOD | BPF_X) || + insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { + /* due to JIT bugs clear upper 32-bits of src register + * before div/mod operation + */ + insn_buf[0] = BPF_MOV32_REG(insn->src_reg, insn->src_reg); + insn_buf[1] = *insn; + cnt = 2; + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + if (insn->code != (BPF_JMP | BPF_CALL)) continue; |