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Commit 84c1cf62 authored by Pekka Enberg's avatar Pekka Enberg
Browse files

SLUB: Fix merged slab cache names 



As explained by Linus "I'm Proud to be an American" Torvalds:

  Looking at the merging code, I actually think it's totally
  buggy. If you have something like this:

   - load module A: create slab cache A

   - load module B: create slab cache B that can merge with A

   - unload module A

   - "cat /proc/slabinfo": BOOM. Oops.

  exactly because the name is not handled correctly, and you'll have
  module B holding open a slab cache that has a name pointer that points
  to module A that no longer exists.

This patch fixes the problem by using kstrdup() to allocate dynamic memory for
->name of "struct kmem_cache" as suggested by Christoph Lameter.

Acked-by: default avatarChristoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Reported-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>

Conflicts:

	mm/slub.c
parent db210e70

mm/slub.c

+20 −1
Original line number Diff line number Diff line
@@ -209,6 +209,7 @@ static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p) 
							{ return 0; }

static inline void sysfs_slab_remove(struct kmem_cache *s)

{

	kfree(s->name);

	kfree(s);

}
@@ -3169,6 +3170,16 @@ void __init kmem_cache_init(void) 
	slab_state = UP;



	/* Provide the correct kmalloc names now that the caches are up */

	if (KMALLOC_MIN_SIZE <= 32) {

		kmalloc_caches[1]->name = kstrdup(kmalloc_caches[1]->name, GFP_NOWAIT);

		BUG_ON(!kmalloc_caches[1]->name);

	}



	if (KMALLOC_MIN_SIZE <= 64) {

		kmalloc_caches[2]->name = kstrdup(kmalloc_caches[2]->name, GFP_NOWAIT);

		BUG_ON(!kmalloc_caches[2]->name);

	}



	for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {

		char *s = kasprintf(GFP_NOWAIT, "kmalloc-%d", 1 << i);
@@ -3271,6 +3282,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, 
		size_t align, unsigned long flags, void (*ctor)(void *))

{

	struct kmem_cache *s;

	char *n;



	if (WARN_ON(!name))

		return NULL;
@@ -3294,19 +3306,25 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, 
		return s;

	}



	n = kstrdup(name, GFP_KERNEL);

	if (!n)

		goto err;



	s = kmalloc(kmem_size, GFP_KERNEL);

	if (s) {

		if (kmem_cache_open(s, name,

		if (kmem_cache_open(s, n,

				size, align, flags, ctor)) {

			list_add(&s->list, &slab_caches);

			if (sysfs_slab_add(s)) {

				list_del(&s->list);

				kfree(n);

				kfree(s);

				goto err;

			}

			up_write(&slub_lock);

			return s;

		}

		kfree(n);

		kfree(s);

	}

	up_write(&slub_lock);
@@ -4439,6 +4457,7 @@ static void kmem_cache_release(struct kobject *kobj) 
{

	struct kmem_cache *s = to_slab(kobj);



	kfree(s->name);

	kfree(s);

}