On 03/30, Andi Kleen wrote:
>
> --- linux-2.6.35.y.orig/kernel/signal.c       2011-03-29 22:50:25.616602954 
> -0700
> +++ linux-2.6.35.y/kernel/signal.c    2011-03-29 23:03:02.941224912 -0700
> @@ -2410,9 +2410,13 @@
>               return -EFAULT;
>
>       /* Not even root can pretend to send signals from the kernel.
> -        Nor can they impersonate a kill(), which adds source info.  */
> -     if (info.si_code >= 0)
> +      * Nor can they impersonate a kill()/tgkill(), which adds source info.
> +      */
> +     if (info.si_code != SI_QUEUE) {
> +             /* We used to allow any < 0 si_code */
> +             WARN_ON_ONCE(info.si_code < 0);
>               return -EPERM;

Oh, please don't.

Quoting Roland:

        Commit da48524eb206 ("Prevent rt_sigqueueinfo and rt_tgsigqueueinfo
        from spoofing the signal code") made the check on si_code too strict:
        glibc's aio implementation wants to queue signals with SI_ASYNCIO, and
        indeed glibc's tst-aio4 fails with the patched kernel.

If stable needs this change, then it probably needs

        Relax si_code check in rt_sigqueueinfo and rt_tgsigqueueinfo
        commit 243b422af9ea9af4ead07a8ad54c90d4f9b6081a

as well.

Oleg.

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