From mboxrd@z Thu Jan 1 00:00:00 1970 From: Markos Chandras Subject: [PATCH 05/17] MIPS: bpf: Return error code if the offset is a negative number Date: Mon, 23 Jun 2014 10:38:48 +0100 Message-ID: <1403516340-22997-6-git-send-email-markos.chandras@imgtec.com> References: <1403516340-22997-1-git-send-email-markos.chandras@imgtec.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Markos Chandras , "David S. Miller" , Daniel Borkmann , "Alexei Starovoitov" , To: Return-path: Received: from mailapp01.imgtec.com ([195.59.15.196]:50037 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752671AbaFWJj3 (ORCPT ); Mon, 23 Jun 2014 05:39:29 -0400 In-Reply-To: <1403516340-22997-1-git-send-email-markos.chandras@imgtec.com> Sender: netdev-owner@vger.kernel.org List-ID: Previously, the negative offset was not checked leading to failures due to trying to load data beyond the skb struct boundaries. Until we have proper asm helpers in place, it's best if we return ENOSUPP if K is negative when trying to JIT the filter or 0 during runtime if we do an indirect load where the value of X is unknown during build time. Cc: "David S. Miller" Cc: Daniel Borkmann Cc: Alexei Starovoitov Cc: netdev@vger.kernel.org Signed-off-by: Markos Chandras --- arch/mips/net/bpf_jit.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c index 5cc92c4590cb..95728ea6cb74 100644 --- a/arch/mips/net/bpf_jit.c +++ b/arch/mips/net/bpf_jit.c @@ -331,6 +331,12 @@ static inline void emit_srl(unsigned int dst, unsigned int src, emit_instr(ctx, srl, dst, src, sa); } +static inline void emit_slt(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, slt, dst, src1, src2); +} + static inline void emit_sltu(unsigned int dst, unsigned int src1, unsigned int src2, struct jit_ctx *ctx) { @@ -816,8 +822,21 @@ static int build_body(struct jit_ctx *ctx) /* A <- P[k:1] */ load_order = 0; load: + /* the interpreter will deal with the negative K */ + if ((int)k < 0) + return -ENOTSUPP; + emit_load_imm(r_off, k, ctx); load_common: + /* + * We may got here from the indirect loads so + * return if offset is negative. + */ + emit_slt(r_s0, r_off, r_zero, ctx); + emit_bcond(MIPS_COND_NE, r_s0, r_zero, + b_imm(prog->len, ctx), ctx); + emit_reg_move(r_ret, r_zero, ctx); + ctx->flags |= SEEN_CALL | SEEN_OFF | SEEN_S0 | SEEN_SKB | SEEN_A; @@ -880,6 +899,10 @@ load_ind: emit_load(r_X, r_skb, off, ctx); break; case BPF_LDX | BPF_B | BPF_MSH: + /* the interpreter will deal with the negative K */ + if ((int)k < 0) + return -ENOTSUPP; + /* X <- 4 * (P[k:1] & 0xf) */ ctx->flags |= SEEN_X | SEEN_CALL | SEEN_S0 | SEEN_SKB; /* Load offset to a1 */ -- 2.0.0