From patchwork Wed Nov 18 08:56:02 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zi Shen Lim X-Patchwork-Id: 56919 Delivered-To: patch@linaro.org Received: by 10.112.155.196 with SMTP id vy4csp2438108lbb; Wed, 18 Nov 2015 00:56:24 -0800 (PST) X-Received: by 10.66.132.37 with SMTP id or5mr469738pab.5.1447836983987; Wed, 18 Nov 2015 00:56:23 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. 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[73.223.118.172]) by smtp.gmail.com with ESMTPSA id in6sm2602592pbd.86.2015.11.18.00.56.14 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 18 Nov 2015 00:56:15 -0800 (PST) From: Zi Shen Lim To: davem@davemloft.net, ast@kernel.org, catalin.marinas@arm.com, will.deacon@arm.com Cc: Zi Shen Lim , daniel@iogearbox.net, yang.shi@linaro.org, xi.wang@gmail.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org Subject: [PATCH] arm64: bpf: fix buffer pointer Date: Wed, 18 Nov 2015 00:56:02 -0800 Message-Id: <1447836962-4086-1-git-send-email-zlim.lnx@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During code review, I noticed we were passing a bad buffer pointer to bpf_load_pointer helper function called by jitted code. Point to the buffer allocated by JIT, so we don't silently corrupt other parts of the stack. Signed-off-by: Zi Shen Lim --- arch/arm64/net/bpf_jit_comp.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ Acked-by: Yang Shi diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index d6a53ef..7cf032b 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -139,6 +139,12 @@ static inline int epilogue_offset(const struct jit_ctx *ctx) /* Stack must be multiples of 16B */ #define STACK_ALIGN(sz) (((sz) + 15) & ~15) +#define _STACK_SIZE \ + (MAX_BPF_STACK \ + + 4 /* extra for skb_copy_bits buffer */) + +#define STACK_SIZE STACK_ALIGN(_STACK_SIZE) + static void build_prologue(struct jit_ctx *ctx) { const u8 r6 = bpf2a64[BPF_REG_6]; @@ -150,10 +156,6 @@ static void build_prologue(struct jit_ctx *ctx) const u8 rx = bpf2a64[BPF_REG_X]; const u8 tmp1 = bpf2a64[TMP_REG_1]; const u8 tmp2 = bpf2a64[TMP_REG_2]; - int stack_size = MAX_BPF_STACK; - - stack_size += 4; /* extra for skb_copy_bits buffer */ - stack_size = STACK_ALIGN(stack_size); /* * BPF prog stack layout @@ -165,12 +167,13 @@ static void build_prologue(struct jit_ctx *ctx) * | ... | callee saved registers * +-----+ * | | x25/x26 - * BPF fp register => -80:+-----+ + * BPF fp register => -80:+-----+ <= (BPF_FP) * | | * | ... | BPF prog stack * | | - * | | - * current A64_SP => +-----+ + * +-----+ <= (BPF_FP - MAX_BPF_STACK) + * |RSVD | JIT scratchpad + * current A64_SP => +-----+ <= (BPF_FP - STACK_SIZE) * | | * | ... | Function call stack * | | @@ -196,7 +199,7 @@ static void build_prologue(struct jit_ctx *ctx) emit(A64_MOV(1, fp, A64_SP), ctx); /* Set up function call stack */ - emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx); + emit(A64_SUB_I(1, A64_SP, A64_SP, STACK_SIZE), ctx); /* Clear registers A and X */ emit_a64_mov_i64(ra, 0, ctx); @@ -213,13 +216,9 @@ static void build_epilogue(struct jit_ctx *ctx) const u8 fp = bpf2a64[BPF_REG_FP]; const u8 tmp1 = bpf2a64[TMP_REG_1]; const u8 tmp2 = bpf2a64[TMP_REG_2]; - int stack_size = MAX_BPF_STACK; - - stack_size += 4; /* extra for skb_copy_bits buffer */ - stack_size = STACK_ALIGN(stack_size); /* We're done with BPF stack */ - emit(A64_ADD_I(1, A64_SP, A64_SP, stack_size), ctx); + emit(A64_ADD_I(1, A64_SP, A64_SP, STACK_SIZE), ctx); /* Restore fs (x25) and x26 */ emit(A64_POP(fp, A64_R(26), A64_SP), ctx); @@ -658,7 +657,7 @@ emit_cond_jmp: return -EINVAL; } emit_a64_mov_i64(r3, size, ctx); - emit(A64_ADD_I(1, r4, fp, MAX_BPF_STACK), ctx); + emit(A64_SUB_I(1, r4, fp, STACK_SIZE), ctx); emit_a64_mov_i64(r5, (unsigned long)bpf_load_pointer, ctx); emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx); emit(A64_MOV(1, A64_FP, A64_SP), ctx);