diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2018-01-30 03:37:42 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-03 17:04:24 +0100 |
| commit | 7dcda40e52ff0712a2d7d5353c1722cb1f994330 (patch) | |
| tree | acb34785034a37a8802bb36efaae8d3703a01d49 /kernel | |
| parent | 28c486744e6de4d882a1d853aa63d99fcba4b7a6 (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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 a62679711de0..32af15136bf4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1165,6 +1165,11 @@ static int check_alu_op(struct verifier_env *env, 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; |