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SubjectRe: [PATCH] arm64: bpf: fix div-by-zero case
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On Wed, Nov 4, 2015 at 10:21 AM, Shi, Yang <yang.shi@linaro.org> wrote:
> On 11/3/2015 11:04 PM, Xi Wang wrote:
>>
>> On Tue, Nov 3, 2015 at 10:56 PM, Zi Shen Lim <zlim.lnx@gmail.com> 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-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>


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