Re: suppress page allocation failure warnings from sys_listxattr
From: Dave Jones
Date: Wed Mar 28 2012 - 22:08:32 EST
On Wed, Mar 28, 2012 at 07:02:11PM -0700, Andrew Morton wrote:
> > Also, what happens if something allocates
> > and sits on a bunch of vmalloc'd memory ? would we start seeing oom kills ?
> vmalloc() would fail.
Ok, that's a pretty boring failure mode, so not a big deal probably.
> > (thinking of the context of my fuzzing tool where a bunch of instances could
> > feasibly call these syscalls and not sit on huge amounts per thread, but
> > collectively... I'm wondering if it could be provoked into killing
> > processes I don't own)
> umm, if you wanted to deliberately trigger a vmalloc() failure then I
> guess a good approach would be to locate a vmalloc() site which can
> persist beyond the syscall (modprobe is a good one!) then exercise it
> in a way so that there are no N-byte holes left in the arena, then
> trigger an N-byte vmalloc().
Well modprobe is root-only, so that's not so bad. But it looks like
key_add (see other thread from this evening) and probably others can be
called as a user and gobble up vmalloc space. omnomnom.
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