Re: Is this a kernel BUG? ///Re: [Question] Can we use SIGRTMIN when vdso disabled on X86?

Leizhen (ThunderTown)
2018-06-06T09:18:11Z

I found that glibc has already dealt with this case. So this issue must have been met before, should it be maintained by libc/user?

if (GLRO(dl_sysinfo_dso) == NULL)
{
kact.sa_flags |= SA_RESTORER;

kact.sa_restorer = ((act->sa_flags & SA_SIGINFO)
? &restore_rt : &restore);
}

On 2018/6/6 15:52, Leizhen (ThunderTown) wrote:
>
>
> On 2018/6/5 19:24, Leizhen (ThunderTown) wrote:
>> After I executed "echo 0 > /proc/sys/abi/vsyscall32" to disable vdso, the rt_sigaction01 test case from ltp_2015 failed.
>> The test case source code please refer to the attachment, and the output as blow:
>>
>> -----------------
>> ./rt_sigaction01
>> rt_sigaction01 0 TINFO : signal: 34
>> rt_sigaction01 1 TPASS : rt_sigaction call succeeded: result = 0
>> rt_sigaction01 0 TINFO : sa.sa_flags = SA_RESETHAND|SA_SIGINFO
>> rt_sigaction01 0 TINFO : Signal Handler Called with signal number 34
>>
>> Segmentation fault
>> ------------------
>>
>>
>> Is this the desired result? In function ia32_setup_rt_frame, I found below code:
>>
>> if (ksig->ka.sa.sa_flags & SA_RESTORER)
>> restorer = ksig->ka.sa.sa_restorer;
>> else
>> restorer = current->mm->context.vdso +
>> vdso_image_32.sym___kernel_rt_sigreturn;
>> put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
>>
>> Because the vdso is disabled, so current->mm->context.vdso is NULL, which cause the result of frame->pretcode invalid.
>>
>> I'm not sure whether this is a kernel bug or just an error of test case itself. Can anyone help me?
>>
>

--
Thanks!
BestRegards