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SubjectRe: [PATCH] [226/275] Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal code
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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