[4.2.y-ckt stable] Patch "arm64: bpf: fix div-by-zero case" has been added to staging queue
This is a note to let you know that I have just added a patch titled arm64: bpf: fix div-by-zero case to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt1. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal -- >From 2d1726efaefaee9e95587f83a3b15e18c5d8f436 Mon Sep 17 00:00:00 2001 From: Zi Shen Lim Date: Tue, 3 Nov 2015 22:56:44 -0800 Subject: arm64: bpf: fix div-by-zero case commit 251599e1d6906621f49218d7b474ddd159e58f3b upstream. In the case of division by zero in a BPF program: A = A / X; (X == 0) the expected behavior is to terminate with return value 0. This is confirmed by the test case introduced in commit 86bf1721b226 ("test_bpf: add tests checking that JIT/interpreter sets A and X to 0."). Reported-by: Yang Shi Tested-by: Yang Shi CC: Xi Wang CC: Alexei Starovoitov CC: linux-arm-ker...@lists.infradead.org CC: linux-kernel@vger.kernel.org Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") Signed-off-by: Zi Shen Lim Signed-off-by: Catalin Marinas Signed-off-by: Kamal Mostafa --- arch/arm64/net/bpf_jit.h | 3 ++- arch/arm64/net/bpf_jit_comp.c | 37 + 2 files changed, 27 insertions(+), 13 deletions(-) diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h index 98a26ce..aee5637 100644 --- a/arch/arm64/net/bpf_jit.h +++ b/arch/arm64/net/bpf_jit.h @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim + * Copyright (C) 2014-2015 Zi Shen Lim * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -35,6 +35,7 @@ aarch64_insn_gen_comp_branch_imm(0, offset, Rt, A64_VARIANT(sf), \ AARCH64_INSN_BRANCH_COMP_##type) #define A64_CBZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, ZERO) +#define A64_CBNZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, NONZERO) /* Conditional branch (immediate) */ #define A64_COND_BRANCH(cond, offset) \ diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index c047598..9ae6f23 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim + * Copyright (C) 2014-2015 Zi Shen Lim * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -225,6 +225,17 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) u8 jmp_cond; s32 jmp_offset; +#define check_imm(bits, imm) do { \ + if imm) > 0) && ((imm) >> (bits))) || \ + (((imm) < 0) && (~(imm) >> (bits { \ + pr_info("[%2d] imm=%d(0x%x) out of range\n",\ + i, imm, imm); \ + return -EINVAL; \ + } \ +} while (0) +#define check_imm19(imm) check_imm(19, imm) +#define check_imm26(imm) check_imm(26, imm) + switch (code) { /* dst = src */ case BPF_ALU | BPF_MOV | BPF_X: @@ -258,8 +269,21 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) break; case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: + { + const u8 r0 = bpf2a64[BPF_REG_0]; + + /* if (src == 0) return 0 */ + jmp_offset = 3; /* skip ahead to else path */ + check_imm19(jmp_offset); + emit(A64_CBNZ(is64, src, jmp_offset), ctx); + emit(A64_MOVZ(1, r0, 0, 0), ctx); + jmp_offset = epilogue_offset(ctx); + check_imm26(jmp_offset); + emit(A64_B(jmp_offset), ctx); + /* else */ emit(A64_UDIV(is64, dst, dst, src), ctx); break; + } case BPF_ALU | BPF_MOD | BPF_X: case BPF_ALU64 | BPF_MOD | BPF_X: ctx->tmp_used = 1; @@ -393,17 +417,6 @@ emit_bswap_uxt: emit(A64_ASR(is64, dst, dst, imm), ctx); break; -#define check_imm(bits, imm) do { \ - if imm) > 0) && ((imm) >> (bits))) || \ - (((imm) < 0) && (~(imm) >> (bits { \ - pr_info("[%2d] imm=%d(0x%x) out of range\n",\ - i, imm, imm); \ - return -EINVAL;
[3.19.y-ckt stable] Patch "arm64: bpf: fix div-by-zero case" has been added to staging queue
This is a note to let you know that I have just added a patch titled arm64: bpf: fix div-by-zero case to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal -- >From eb0c40a4a3aef5b7997b29196511e36cd9234915 Mon Sep 17 00:00:00 2001 From: Zi Shen Lim Date: Tue, 3 Nov 2015 22:56:44 -0800 Subject: arm64: bpf: fix div-by-zero case commit 251599e1d6906621f49218d7b474ddd159e58f3b upstream. In the case of division by zero in a BPF program: A = A / X; (X == 0) the expected behavior is to terminate with return value 0. This is confirmed by the test case introduced in commit 86bf1721b226 ("test_bpf: add tests checking that JIT/interpreter sets A and X to 0."). Reported-by: Yang Shi Tested-by: Yang Shi CC: Xi Wang CC: Alexei Starovoitov CC: linux-arm-ker...@lists.infradead.org CC: linux-kernel@vger.kernel.org Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") Signed-off-by: Zi Shen Lim Signed-off-by: Catalin Marinas Signed-off-by: Kamal Mostafa --- arch/arm64/net/bpf_jit.h | 3 ++- arch/arm64/net/bpf_jit_comp.c | 37 + 2 files changed, 27 insertions(+), 13 deletions(-) diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h index 98a26ce..aee5637 100644 --- a/arch/arm64/net/bpf_jit.h +++ b/arch/arm64/net/bpf_jit.h @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim + * Copyright (C) 2014-2015 Zi Shen Lim * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -35,6 +35,7 @@ aarch64_insn_gen_comp_branch_imm(0, offset, Rt, A64_VARIANT(sf), \ AARCH64_INSN_BRANCH_COMP_##type) #define A64_CBZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, ZERO) +#define A64_CBNZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, NONZERO) /* Conditional branch (immediate) */ #define A64_COND_BRANCH(cond, offset) \ diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index c047598..9ae6f23 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim + * Copyright (C) 2014-2015 Zi Shen Lim * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -225,6 +225,17 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) u8 jmp_cond; s32 jmp_offset; +#define check_imm(bits, imm) do { \ + if imm) > 0) && ((imm) >> (bits))) || \ + (((imm) < 0) && (~(imm) >> (bits { \ + pr_info("[%2d] imm=%d(0x%x) out of range\n",\ + i, imm, imm); \ + return -EINVAL; \ + } \ +} while (0) +#define check_imm19(imm) check_imm(19, imm) +#define check_imm26(imm) check_imm(26, imm) + switch (code) { /* dst = src */ case BPF_ALU | BPF_MOV | BPF_X: @@ -258,8 +269,21 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) break; case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: + { + const u8 r0 = bpf2a64[BPF_REG_0]; + + /* if (src == 0) return 0 */ + jmp_offset = 3; /* skip ahead to else path */ + check_imm19(jmp_offset); + emit(A64_CBNZ(is64, src, jmp_offset), ctx); + emit(A64_MOVZ(1, r0, 0, 0), ctx); + jmp_offset = epilogue_offset(ctx); + check_imm26(jmp_offset); + emit(A64_B(jmp_offset), ctx); + /* else */ emit(A64_UDIV(is64, dst, dst, src), ctx); break; + } case BPF_ALU | BPF_MOD | BPF_X: case BPF_ALU64 | BPF_MOD | BPF_X: ctx->tmp_used = 1; @@ -393,17 +417,6 @@ emit_bswap_uxt: emit(A64_ASR(is64, dst, dst, imm), ctx); break; -#define check_imm(bits, imm) do { \ - if imm) > 0) && ((imm) >> (bits))) || \ - (((imm) < 0) && (~(imm) >> (bits { \ - pr_info("[%2d] imm=%d(0x%x) out of range\n",\ - i, imm, imm); \ - return -EINVAL;
Re: [PATCH] arm64: bpf: fix div-by-zero case
On 11/04/2015 07:41 PM, Shi, Yang wrote: ... Agreed, and we may need add one more test cases in test_bpf module to cover MOD? Let me know if you have a test case ready :) Does the below change look like a valid test? + "MOD default X", + .u.insns = { + /* +* A = 0x42 +* A = A mod X ; this halt the filter execution if X is 0 +* ret 0x42 +*/ + BPF_STMT(BPF_LD | BPF_IMM, 0x42), + BPF_STMT(BPF_ALU | BPF_MOD | BPF_X, 0), + BPF_STMT(BPF_RET | BPF_K, 0x42), + }, + CLASSIC | FLAG_NO_DATA, + {}, + { {0x1, 0x0 } }, + }, + { + "MOD default A", + .u.insns = { + /* +* A = A mod 1 +* ret A +*/ + BPF_STMT(BPF_ALU | BPF_MOD | BPF_K, 0x1), + BPF_STMT(BPF_RET | BPF_A, 0x0), + }, + CLASSIC | FLAG_NO_DATA, + {}, + { {0x1, 0x0 } }, + }, My test result with it: test_bpf: #284 MOD default X jited:1 ret 66 != 0 FAIL (1 times) test_bpf: #285 MOD default A jited:1 102 PASS If it looks right, I will post a patch to add the test cases. Looks good to me. Thanks, Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] arm64: bpf: fix div-by-zero case
On Wed, Nov 4, 2015 at 10:21 AM, Shi, Yang wrote: > On 11/3/2015 11:04 PM, Xi Wang wrote: >> >> On Tue, Nov 3, 2015 at 10:56 PM, Zi Shen Lim wrote: >>> >>> case BPF_ALU | BPF_DIV | BPF_X: >>> case BPF_ALU64 | BPF_DIV | BPF_X: >>> + { >>> + const u8 r0 = bpf2a64[BPF_REG_0]; >>> + >>> + /* if (src == 0) return 0 */ >>> + jmp_offset = 3; /* skip ahead to else path */ >>> + check_imm19(jmp_offset); >>> + emit(A64_CBNZ(is64, src, jmp_offset), ctx); >>> + emit(A64_MOVZ(1, r0, 0, 0), ctx); >>> + jmp_offset = epilogue_offset(ctx); >>> + check_imm26(jmp_offset); >>> + emit(A64_B(jmp_offset), ctx); >>> + /* else */ >>> emit(A64_UDIV(is64, dst, dst, src), ctx); >>> break; >>> + } >>> case BPF_ALU | BPF_MOD | BPF_X: >>> case BPF_ALU64 | BPF_MOD | BPF_X: >> >> >> BPF_MOD might need the same fix. I'll post a fix for this case as well. > > > Agreed, and we may need add one more test cases in test_bpf module to cover > MOD? Let me know if you have a test case ready :) > > Yang > >> >> ___ >> linux-arm-kernel mailing list >> linux-arm-ker...@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] arm64: bpf: fix div-by-zero case
On 11/4/2015 10:25 AM, Z Lim wrote: On Wed, Nov 4, 2015 at 10:21 AM, Shi, Yang wrote: On 11/3/2015 11:04 PM, Xi Wang wrote: On Tue, Nov 3, 2015 at 10:56 PM, Zi Shen Lim wrote: case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: + { + const u8 r0 = bpf2a64[BPF_REG_0]; + + /* if (src == 0) return 0 */ + jmp_offset = 3; /* skip ahead to else path */ + check_imm19(jmp_offset); + emit(A64_CBNZ(is64, src, jmp_offset), ctx); + emit(A64_MOVZ(1, r0, 0, 0), ctx); + jmp_offset = epilogue_offset(ctx); + check_imm26(jmp_offset); + emit(A64_B(jmp_offset), ctx); + /* else */ emit(A64_UDIV(is64, dst, dst, src), ctx); break; + } case BPF_ALU | BPF_MOD | BPF_X: case BPF_ALU64 | BPF_MOD | BPF_X: BPF_MOD might need the same fix. I'll post a fix for this case as well. Agreed, and we may need add one more test cases in test_bpf module to cover MOD? Let me know if you have a test case ready :) Does the below change look like a valid test? + "MOD default X", + .u.insns = { + /* +* A = 0x42 +* A = A mod X ; this halt the filter execution if X is 0 +* ret 0x42 +*/ + BPF_STMT(BPF_LD | BPF_IMM, 0x42), + BPF_STMT(BPF_ALU | BPF_MOD | BPF_X, 0), + BPF_STMT(BPF_RET | BPF_K, 0x42), + }, + CLASSIC | FLAG_NO_DATA, + {}, + { {0x1, 0x0 } }, + }, + { + "MOD default A", + .u.insns = { + /* +* A = A mod 1 +* ret A +*/ + BPF_STMT(BPF_ALU | BPF_MOD | BPF_K, 0x1), + BPF_STMT(BPF_RET | BPF_A, 0x0), + }, + CLASSIC | FLAG_NO_DATA, + {}, + { {0x1, 0x0 } }, + }, My test result with it: test_bpf: #284 MOD default X jited:1 ret 66 != 0 FAIL (1 times) test_bpf: #285 MOD default A jited:1 102 PASS If it looks right, I will post a patch to add the test cases. Thanks, Yang Yang ___ linux-arm-kernel mailing list linux-arm-ker...@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] arm64: bpf: fix div-by-zero case
On 11/3/2015 11:04 PM, Xi Wang wrote: On Tue, Nov 3, 2015 at 10:56 PM, Zi Shen Lim wrote: case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: + { + const u8 r0 = bpf2a64[BPF_REG_0]; + + /* if (src == 0) return 0 */ + jmp_offset = 3; /* skip ahead to else path */ + check_imm19(jmp_offset); + emit(A64_CBNZ(is64, src, jmp_offset), ctx); + emit(A64_MOVZ(1, r0, 0, 0), ctx); + jmp_offset = epilogue_offset(ctx); + check_imm26(jmp_offset); + emit(A64_B(jmp_offset), ctx); + /* else */ emit(A64_UDIV(is64, dst, dst, src), ctx); break; + } case BPF_ALU | BPF_MOD | BPF_X: case BPF_ALU64 | BPF_MOD | BPF_X: BPF_MOD might need the same fix. Agreed, and we may need add one more test cases in test_bpf module to cover MOD? Yang ___ linux-arm-kernel mailing list linux-arm-ker...@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] arm64: bpf: fix div-by-zero case
On 11/3/2015 10:56 PM, Zi Shen Lim wrote: In the case of division by zero in a BPF program: A = A / X; (X == 0) the expected behavior is to terminate with return value 0. This is confirmed by the test case introduced in commit 86bf1721b226 ("test_bpf: add tests checking that JIT/interpreter sets A and X to 0."). Reported-by: Shi, Yang Thanks for coming up with the fix promptly. s/Shi, Yang/Yang Shi Tested with the latest 4.3 kernel. Tested-by: Yang Shi Yang CC: Xi Wang CC: Alexei Starovoitov CC: Catalin Marinas CC: linux-arm-ker...@lists.infradead.org CC: linux-kernel@vger.kernel.org Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") Cc: # 3.18+ Signed-off-by: Zi Shen Lim --- arch/arm64/net/bpf_jit.h | 3 ++- arch/arm64/net/bpf_jit_comp.c | 37 + 2 files changed, 27 insertions(+), 13 deletions(-) diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h index 98a26ce..aee5637 100644 --- a/arch/arm64/net/bpf_jit.h +++ b/arch/arm64/net/bpf_jit.h @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim + * Copyright (C) 2014-2015 Zi Shen Lim * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -35,6 +35,7 @@ aarch64_insn_gen_comp_branch_imm(0, offset, Rt, A64_VARIANT(sf), \ AARCH64_INSN_BRANCH_COMP_##type) #define A64_CBZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, ZERO) +#define A64_CBNZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, NONZERO) /* Conditional branch (immediate) */ #define A64_COND_BRANCH(cond, offset) \ diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index c047598..9ae6f23 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim + * Copyright (C) 2014-2015 Zi Shen Lim * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -225,6 +225,17 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) u8 jmp_cond; s32 jmp_offset; +#define check_imm(bits, imm) do { \ + if imm) > 0) && ((imm) >> (bits))) || \ + (((imm) < 0) && (~(imm) >> (bits { \ + pr_info("[%2d] imm=%d(0x%x) out of range\n", \ + i, imm, imm); \ + return -EINVAL; \ + } \ +} while (0) +#define check_imm19(imm) check_imm(19, imm) +#define check_imm26(imm) check_imm(26, imm) + switch (code) { /* dst = src */ case BPF_ALU | BPF_MOV | BPF_X: @@ -258,8 +269,21 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) break; case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: + { + const u8 r0 = bpf2a64[BPF_REG_0]; + + /* if (src == 0) return 0 */ + jmp_offset = 3; /* skip ahead to else path */ + check_imm19(jmp_offset); + emit(A64_CBNZ(is64, src, jmp_offset), ctx); + emit(A64_MOVZ(1, r0, 0, 0), ctx); + jmp_offset = epilogue_offset(ctx); + check_imm26(jmp_offset); + emit(A64_B(jmp_offset), ctx); + /* else */ emit(A64_UDIV(is64, dst, dst, src), ctx); break; + } case BPF_ALU | BPF_MOD | BPF_X: case BPF_ALU64 | BPF_MOD | BPF_X: ctx->tmp_used = 1; @@ -393,17 +417,6 @@ emit_bswap_uxt: emit(A64_ASR(is64, dst, dst, imm), ctx); break; -#define check_imm(bits, imm) do { \ - if imm) > 0) && ((imm) >> (bits))) || \ - (((imm) < 0) && (~(imm) >> (bits { \ - pr_info("[%2d] imm=%d(0x%x) out of range\n", \ - i, imm, imm); \ - return -EINVAL; \ - } \ -} while (0) -#define check_imm19(imm) check_imm(19, imm) -#define check_imm26(imm) check_imm(26, imm) - /* JUMP off */ case BPF_JMP | BPF_JA: jmp_offset = bpf2a64_offset(i + off, i, ctx); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] arm64: bpf: fix div-by-zero case
On Tue, Nov 3, 2015 at 10:56 PM, Zi Shen Lim wrote: > case BPF_ALU | BPF_DIV | BPF_X: > case BPF_ALU64 | BPF_DIV | BPF_X: > + { > + const u8 r0 = bpf2a64[BPF_REG_0]; > + > + /* if (src == 0) return 0 */ > + jmp_offset = 3; /* skip ahead to else path */ > + check_imm19(jmp_offset); > + emit(A64_CBNZ(is64, src, jmp_offset), ctx); > + emit(A64_MOVZ(1, r0, 0, 0), ctx); > + jmp_offset = epilogue_offset(ctx); > + check_imm26(jmp_offset); > + emit(A64_B(jmp_offset), ctx); > + /* else */ > emit(A64_UDIV(is64, dst, dst, src), ctx); > break; > + } > case BPF_ALU | BPF_MOD | BPF_X: > case BPF_ALU64 | BPF_MOD | BPF_X: BPF_MOD might need the same fix. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] arm64: bpf: fix div-by-zero case
In the case of division by zero in a BPF program: A = A / X; (X == 0) the expected behavior is to terminate with return value 0. This is confirmed by the test case introduced in commit 86bf1721b226 ("test_bpf: add tests checking that JIT/interpreter sets A and X to 0."). Reported-by: Shi, Yang CC: Xi Wang CC: Alexei Starovoitov CC: Catalin Marinas CC: linux-arm-ker...@lists.infradead.org CC: linux-kernel@vger.kernel.org Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") Cc: # 3.18+ Signed-off-by: Zi Shen Lim --- arch/arm64/net/bpf_jit.h | 3 ++- arch/arm64/net/bpf_jit_comp.c | 37 + 2 files changed, 27 insertions(+), 13 deletions(-) diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h index 98a26ce..aee5637 100644 --- a/arch/arm64/net/bpf_jit.h +++ b/arch/arm64/net/bpf_jit.h @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim + * Copyright (C) 2014-2015 Zi Shen Lim * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -35,6 +35,7 @@ aarch64_insn_gen_comp_branch_imm(0, offset, Rt, A64_VARIANT(sf), \ AARCH64_INSN_BRANCH_COMP_##type) #define A64_CBZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, ZERO) +#define A64_CBNZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, NONZERO) /* Conditional branch (immediate) */ #define A64_COND_BRANCH(cond, offset) \ diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index c047598..9ae6f23 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014 Zi Shen Lim + * Copyright (C) 2014-2015 Zi Shen Lim * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -225,6 +225,17 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) u8 jmp_cond; s32 jmp_offset; +#define check_imm(bits, imm) do { \ + if imm) > 0) && ((imm) >> (bits))) || \ + (((imm) < 0) && (~(imm) >> (bits { \ + pr_info("[%2d] imm=%d(0x%x) out of range\n",\ + i, imm, imm); \ + return -EINVAL; \ + } \ +} while (0) +#define check_imm19(imm) check_imm(19, imm) +#define check_imm26(imm) check_imm(26, imm) + switch (code) { /* dst = src */ case BPF_ALU | BPF_MOV | BPF_X: @@ -258,8 +269,21 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) break; case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: + { + const u8 r0 = bpf2a64[BPF_REG_0]; + + /* if (src == 0) return 0 */ + jmp_offset = 3; /* skip ahead to else path */ + check_imm19(jmp_offset); + emit(A64_CBNZ(is64, src, jmp_offset), ctx); + emit(A64_MOVZ(1, r0, 0, 0), ctx); + jmp_offset = epilogue_offset(ctx); + check_imm26(jmp_offset); + emit(A64_B(jmp_offset), ctx); + /* else */ emit(A64_UDIV(is64, dst, dst, src), ctx); break; + } case BPF_ALU | BPF_MOD | BPF_X: case BPF_ALU64 | BPF_MOD | BPF_X: ctx->tmp_used = 1; @@ -393,17 +417,6 @@ emit_bswap_uxt: emit(A64_ASR(is64, dst, dst, imm), ctx); break; -#define check_imm(bits, imm) do { \ - if imm) > 0) && ((imm) >> (bits))) || \ - (((imm) < 0) && (~(imm) >> (bits { \ - pr_info("[%2d] imm=%d(0x%x) out of range\n",\ - i, imm, imm); \ - return -EINVAL; \ - } \ -} while (0) -#define check_imm19(imm) check_imm(19, imm) -#define check_imm26(imm) check_imm(26, imm) - /* JUMP off */ case BPF_JMP | BPF_JA: jmp_offset = bpf2a64_offset(i + off, i, ctx); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/