From: Rabin Vincent Date: Tue, 12 Jan 2016 19:17:08 +0000 (+0100) Subject: net: bpf: reject invalid shifts X-Git-Tag: v4.3.5~51 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f2da6274a5f9d858a6a81f1f11966f42e476f1f3;p=thirdparty%2Fkernel%2Fstable.git 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 Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b074b23000d6e..36c6efeffdd53 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1058,6 +1058,16 @@ 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 bb18c36800012..49b44879dc7fb 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -781,6 +781,11 @@ static int bpf_check_classic(const struct sock_filter *filter, 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: