diff options
| author | Rabin Vincent <rabin@rab.in> | 2016-01-12 20:17:08 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-01-31 11:23:37 -0800 |
| commit | dc1cfcc266978d0213d7d4f9f813bafd4e9f709a (patch) | |
| tree | 395be2ee2760343fe564e3a4439df0b367ef15fa | |
| parent | 2a1e5e4ab662a159e7e5dfd229597c4752d29b3c (diff) | |
| download | lwn-dc1cfcc266978d0213d7d4f9f813bafd4e9f709a.tar.gz lwn-dc1cfcc266978d0213d7d4f9f813bafd4e9f709a.zip | |
net: bpf: reject invalid shifts
[ Upstream commit 229394e8e62a4191d592842cf67e80c62a492937 ]
On ARM64, a BUG() is triggered in the eBPF JIT if a filter with a
constant shift that can't be encoded in the immediate field of the
UBFM/SBFM instructions is passed to the JIT. Since these shifts
amounts, which are negative or >= regsize, are invalid, reject them in
the eBPF verifier and the classic BPF filter checker, for all
architectures.
Signed-off-by: Rabin Vincent <rabin@rab.in>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/bpf/verifier.c | 10 | ||||
| -rw-r--r-- | net/core/filter.c | 5 |
2 files changed, 15 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 47dcd3aa6e23..141d562064a7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1019,6 +1019,16 @@ static int check_alu_op(struct reg_state *regs, struct bpf_insn *insn) 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; + + if (insn->imm < 0 || insn->imm >= size) { + verbose("invalid shift %d\n", insn->imm); + return -EINVAL; + } + } + /* pattern match 'bpf_add Rx, imm' instruction */ if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && regs[insn->dst_reg].type == FRAME_PTR && diff --git a/net/core/filter.c b/net/core/filter.c index 0fa2613b5e35..238bb3f9c51d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -775,6 +775,11 @@ int bpf_check_classic(const struct sock_filter *filter, unsigned int flen) if (ftest->k == 0) return -EINVAL; break; + case BPF_ALU | BPF_LSH | BPF_K: + case BPF_ALU | BPF_RSH | BPF_K: + if (ftest->k >= 32) + return -EINVAL; + break; case BPF_LD | BPF_MEM: case BPF_LDX | BPF_MEM: case BPF_ST: |