diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 8301de2d1f9638df765d2da942b1270b66586623..5f35f93dcab26b21ec5b74882116a25868df8399 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -999,14 +999,10 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) (*(s64 *) &DST) >>= IMM; CONT; ALU64_MOD_X: - if (unlikely(SRC == 0)) - return 0; div64_u64_rem(DST, SRC, &tmp); DST = tmp; CONT; ALU_MOD_X: - if (unlikely((u32)SRC == 0)) - return 0; tmp = (u32) DST; DST = do_div(tmp, (u32) SRC); CONT; @@ -1019,13 +1015,9 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) DST = do_div(tmp, (u32) IMM); CONT; ALU64_DIV_X: - if (unlikely(SRC == 0)) - return 0; DST = div64_u64(DST, SRC); CONT; ALU_DIV_X: - if (unlikely((u32)SRC == 0)) - return 0; tmp = (u32) DST; do_div(tmp, (u32) SRC); DST = (u32) tmp; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0c526941509064095bd7b466fc1a543942dc85e3..5fb69a85d9675dcf8a077d20f5314ee78949e884 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5400,15 +5400,37 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) int i, cnt, delta = 0; for (i = 0; i < insn_cnt; i++, insn++) { - if (insn->code == (BPF_ALU | BPF_MOD | BPF_X) || + if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) || + insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) || + insn->code == (BPF_ALU | BPF_MOD | BPF_X) || insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { - /* due to JIT bugs clear upper 32-bits of src register - * before div/mod operation - */ - insn_buf[0] = BPF_MOV32_REG(insn->src_reg, insn->src_reg); - insn_buf[1] = *insn; - cnt = 2; - new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + bool is64 = BPF_CLASS(insn->code) == BPF_ALU64; + struct bpf_insn mask_and_div[] = { + BPF_MOV32_REG(insn->src_reg, insn->src_reg), + /* Rx div 0 -> 0 */ + BPF_JMP_IMM(BPF_JNE, insn->src_reg, 0, 2), + BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg), + BPF_JMP_IMM(BPF_JA, 0, 0, 1), + *insn, + }; + struct bpf_insn mask_and_mod[] = { + BPF_MOV32_REG(insn->src_reg, insn->src_reg), + /* Rx mod 0 -> Rx */ + BPF_JMP_IMM(BPF_JEQ, insn->src_reg, 0, 1), + *insn, + }; + struct bpf_insn *patchlet; + + if (insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) || + insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { + patchlet = mask_and_div + (is64 ? 1 : 0); + cnt = ARRAY_SIZE(mask_and_div) - (is64 ? 1 : 0); + } else { + patchlet = mask_and_mod + (is64 ? 1 : 0); + cnt = ARRAY_SIZE(mask_and_mod) - (is64 ? 1 : 0); + } + + new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt); if (!new_prog) return -ENOMEM; diff --git a/net/core/filter.c b/net/core/filter.c index 60d8c8712652be5263249dd43f8ec57d62975dd3..08ab4c65a998db9458ca92176fbc1e465fde255a 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -459,8 +459,15 @@ static int bpf_convert_filter(struct sock_filter *prog, int len, break; if (fp->code == (BPF_ALU | BPF_DIV | BPF_X) || - fp->code == (BPF_ALU | BPF_MOD | BPF_X)) + fp->code == (BPF_ALU | BPF_MOD | BPF_X)) { *insn++ = BPF_MOV32_REG(BPF_REG_X, BPF_REG_X); + /* Error with exception code on div/mod by 0. + * For cBPF programs, this was always return 0. + */ + *insn++ = BPF_JMP_IMM(BPF_JNE, BPF_REG_X, 0, 2); + *insn++ = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_A); + *insn++ = BPF_EXIT_INSN(); + } *insn = BPF_RAW_INSN(fp->code, BPF_REG_A, BPF_REG_X, 0, fp->k); break;