From: Andrew Morton <akpm@linux-foundation.org>
To: Jack Steiner <steiner@sgi.com>
Cc: mingo@elte.hu, rusty@rustcorp.com.au, sfr@canb.auug.org.au,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] - Fix slab corruption caused by alloc_cpumask_var_node()
Date: Thu, 2 Apr 2009 14:39:32 -0700 [thread overview]
Message-ID: <20090402143932.79a15852.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090402212751.GA11495@sgi.com>
On Thu, 2 Apr 2009 16:27:51 -0500
Jack Steiner <steiner@sgi.com> wrote:
> Fix for slab corruption caused by alloc_cpumask_var_node() overwriting
> the tail end of an off-stack cpumask.
changelog is crappy.
> --- linux.orig/lib/cpumask.c 2009-04-02 15:30:05.000000000 -0500
> +++ linux/lib/cpumask.c 2009-04-02 15:57:44.000000000 -0500
> @@ -109,10 +109,10 @@ bool alloc_cpumask_var_node(cpumask_var_
> #endif
> /* FIXME: Bandaid to save us from old primitives which go to NR_CPUS. */
> if (*mask) {
> + unsigned char *ptr = (unsigned char *)cpumask_bits(*mask);
> unsigned int tail;
> tail = BITS_TO_LONGS(NR_CPUS - nr_cpumask_bits) * sizeof(long);
> - memset(cpumask_bits(*mask) + cpumask_size() - tail,
> - 0, tail);
> + memset(ptr + cpumask_size() - tail, 0, tail);
> }
>
It appears that the bug is that cpumask_bits() returns an `unsigned
long *', except the pointer arithmetic in there is designed to operate
on char*/void*/etc, correct?
This fix is needed in 2.6.29 as well, correct?
next prev parent reply other threads:[~2009-04-02 21:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-02 21:27 [PATCH] - Fix slab corruption caused by alloc_cpumask_var_node() Jack Steiner
2009-04-02 21:39 ` Andrew Morton [this message]
2009-04-02 22:09 ` [PATCH] - Updated: " Jack Steiner
2009-04-02 22:23 ` Ingo Molnar
2009-04-02 21:42 ` [PATCH] - " Ingo Molnar
2009-04-05 5:31 ` Rusty Russell
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