[PATCH] arm64: bpf: fix div-by-zero case
Z Lim
zlim.lnx at gmail.com
Wed Nov 4 10:25:05 PST 2015
On Wed, Nov 4, 2015 at 10:21 AM, Shi, Yang <yang.shi at 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 at 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
>
>>
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>
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