diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2018-01-30 03:37:42 +0100 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@microsoft.com> | 2018-02-28 22:09:45 -0500 |
| commit | 31f1fa710257deb8eb3ec5236fd13562ec39dd22 (patch) | |
| tree | 281b7bb07093b31ff55dbf2dcb85c698aafe406d /kernel | |
| parent | f3ddd4df852f8c2ed11d09086b64a3be76ea2aed (diff) | |
bpf: arsh is not supported in 32 bit alu thus reject it
[ Upstream commit 7891a87efc7116590eaba57acc3c422487802c6f ]
The following snippet was throwing an 'unknown opcode cc' warning
in BPF interpreter:
0: (18) r0 = 0x0
2: (7b) *(u64 *)(r10 -16) = r0
3: (cc) (u32) r0 s>>= (u32) r0
4: (95) exit
Although a number of JITs do support BPF_ALU | BPF_ARSH | BPF_{K,X}
generation, not all of them do and interpreter does neither. We can
leave existing ones and implement it later in bpf-next for the
remaining ones, but reject this properly in verifier for the time
being.
Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)")
Reported-by: syzbot+93c4904c5c70348a6890@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1bdc6f910a1d..03d74868c709 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1020,6 +1020,11 @@ static int check_alu_op(struct reg_state *regs, struct bpf_insn *insn) return -EINVAL; } + if (opcode == BPF_ARSH && BPF_CLASS(insn->code) != BPF_ALU64) { + verbose("BPF_ARSH not supported for 32 bit ALU\n"); + return -EINVAL; + } + if ((opcode == BPF_LSH || opcode == BPF_RSH || opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; |