Re: [PATCH] arm64: bpf: fix div-by-zero case

From: Xi Wang
Date: Wed Nov 04 2015 - 02:05:32 EST


On Tue, Nov 3, 2015 at 10:56 PM, Zi Shen Lim <zlim.lnx@xxxxxxxxx> 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.
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