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Commit d4a5fca5 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm, slab: initialize object alignment on cache creation 

Since commit 45906855 ("mm/sl[aou]b: Common alignment code"), the
"ralign" automatic variable in __kmem_cache_create() may be used as
uninitialized.

The proper alignment defaults to BYTES_PER_WORD and can be overridden by
SLAB_RED_ZONE or the alignment specified by the caller.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=85031



Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Reported-by: default avatarAndrei Elovikov <a.elovikov@gmail.com>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 87e6d49a

mm/slab.c

+2 −9
Original line number Diff line number Diff line
@@ -2124,7 +2124,8 @@ static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp) 
int

__kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)

{

	size_t left_over, freelist_size, ralign;

	size_t left_over, freelist_size;

	size_t ralign = BYTES_PER_WORD;

	gfp_t gfp;

	int err;

	size_t size = cachep->size;
@@ -2157,14 +2158,6 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags) 
		size &= ~(BYTES_PER_WORD - 1);

	}



	/*

	 * Redzoning and user store require word alignment or possibly larger.

	 * Note this will be overridden by architecture or caller mandated

	 * alignment if either is greater than BYTES_PER_WORD.

	 */

	if (flags & SLAB_STORE_USER)

		ralign = BYTES_PER_WORD;



	if (flags & SLAB_RED_ZONE) {

		ralign = REDZONE_ALIGN;

		/* If redzoning, ensure that the second redzone is suitably