[PATCH] ash: clear NONBLOCK flag from stdin when in foreground

[Rich Felker]

On Thu, Aug 25, 2011 at 03:45:33AM +0200, Laurent Bercot wrote:
> On Wed, Aug 24, 2011 at 11:37:11PM +0200, Denys Vlasenko wrote:
> > Got just a few minutes ago in a freshly opened gnome term:
> > 
> > + --------------------------
> > | bash: printf: write error: Interrupted system call
> > | $ _
> > |
> > |
> > 
> > Real world stroke again. EINTR which "can't happen" happened.
> 
>  Absolutely. So let me step in again:
>  http://www.skarnet.org/software/skalibs/libstddjb/safewrappers.html
> 
>  (But I do agree with you, Denys, that the best place to fix stray
> EINTRs would be the kernel.)

Indeed, this is a SERIOUS KERNEL BUG with major security implications.
Expecting every userspace app to work around it is nonsense. If Linus
added *(char *)rand()=rand(); somewhere in the kernel, would you want
every userspace app to work around that too? :-)

I would be interested in seeing how Denys was able to make it happen,
though. I have never seen such a thing and I'm rather skeptical.

Rich