Commit d4a5fca5 authored Sep 25, 2014 by David Rientjes Committed by Linus Torvalds Sep 26, 2014

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: David Rientjes <rientjes@google.com>
Reported-by: Andrei Elovikov <a.elovikov@gmail.com>
Acked-by: Christoph 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus 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

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