From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rabin Vincent Subject: [PATCH] net: bpf: reject invalid shifts Date: Tue, 12 Jan 2016 18:55:07 +0100 Message-ID: <1452621307-2213-1-git-send-email-rabin@rab.in> Cc: netdev@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, linux-arm-kernel@lists.infradead.org, Rabin Vincent To: davem@davemloft.net Return-path: Received: from mail-wm0-f67.google.com ([74.125.82.67]:36633 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752252AbcALRzU (ORCPT ); Tue, 12 Jan 2016 12:55:20 -0500 Received: by mail-wm0-f67.google.com with SMTP id l65so32586084wmf.3 for ; Tue, 12 Jan 2016 09:55:19 -0800 (PST) Sender: netdev-owner@vger.kernel.org List-ID: 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 then in the eBPF verifier and the classic BPF filter checker, for all architectures. Signed-off-by: Rabin Vincent --- 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 a7945d10b378..3643df0dfaa9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1121,6 +1121,16 @@ static int check_alu_op(struct verifier_env *env, struct bpf_insn *insn) return -EINVAL; } + if ((opcode == BPF_LSH || opcode == BPF_RSH) && + 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 672eefbfbe99..37157c4c1a78 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -777,6 +777,11 @@ 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: -- 2.6.4