From ad8a731320c4cfaa80dbfbcbd01d079e09dd92c5 Mon Sep 17 00:00:00 2001 From: Rabin Vincent Date: Tue, 12 Jan 2016 20:17:08 +0100 Subject: [PATCH] net: bpf: reject invalid shifts Orabug: 23330560 [ 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 (cherry picked from commit dc1cfcc266978d0213d7d4f9f813bafd4e9f709a) Signed-off-by: Dan Duval --- kernel/bpf/verifier.c | 10 ++++++++++ net/core/filter.c | 5 +++++ 2 files changed, 15 insertions(+) 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: -- 2.50.1