Re: [PATCH] set*uid() must not fail-and-return on OOM/rlimits

From: Arjan van de Ven
Date: Sun Aug 20 2006 - 12:03:04 EST

On Sun, 2006-08-20 at 19:30 +0400, Solar Designer wrote:
> On Sun, Aug 20, 2006 at 12:07:06PM +0200, Alex Riesen wrote:
> > Solar Designer, Sun, Aug 20, 2006 02:38:40 +0200:
> > > Attached is a trivial patch (extracted from 2.4.33-ow1) that makes
> > > set*uid() kill the current process rather than proceed with -EAGAIN when
> > > the kernel is running out of memory. Apparently, alloc_uid() can't fail
> > > and return anyway due to properties of the allocator, in which case the
> > > patch does not change a thing. But better safe than sorry.
> >
> > Why not ENOMEM?
> ENOMEM would not be any better than EAGAIN from the security standpoint.
> The problem is that there are lots of privileged userspace programs that
> do not bother to check the return value from set*uid() calls (or
> otherwise check that the calls succeeded) before proceeding with work
> that is only safe to do with the *uid switched as intended.

sounds like a good argument to get the setuid functions marked
__must_check in glibc...

if you want to mail me at work (you don't), use arjan (at)

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