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slub: Potential stack overflow

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I discovered that we can overflow stack if CONFIG_SLUB_DEBUG=y and use slabs
with many objects, since list_slab_objects() and process_slab() use
DECLARE_BITMAP(map, page->objects).

With 65535 bits, we use 8192 bytes of stack ...

Switch these allocations to dynamic allocations.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
This commit is contained in:
Eric Dumazet 2010-03-24 22:25:47 +01:00 committed by Pekka Enberg
parent e40152ee1e
commit bbd7d57bfe
1 changed files with 16 additions and 9 deletions
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25
mm/slub.c
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@ -2429,9 +2429,11 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
#ifdef CONFIG_SLUB_DEBUG
void *addr = page_address(page);
void *p;
DECLARE_BITMAP(map, page->objects);
long *map = kzalloc(BITS_TO_LONGS(page->objects) * sizeof(long),
GFP_ATOMIC);
bitmap_zero(map, page->objects);
if (!map)
return;
slab_err(s, page, "%s", text);
slab_lock(page);
for_each_free_object(p, s, page->freelist)
@ -2446,6 +2448,7 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
}
}
slab_unlock(page);
kfree(map);
#endif
}
@ -3651,10 +3654,10 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
}
static void process_slab(struct loc_track *t, struct kmem_cache *s,
struct page *page, enum track_item alloc)
struct page *page, enum track_item alloc,
long *map)
{
void *addr = page_address(page);
DECLARE_BITMAP(map, page->objects);
void *p;
bitmap_zero(map, page->objects);
@ -3673,11 +3676,14 @@ static int list_locations(struct kmem_cache *s, char *buf,
unsigned long i;
struct loc_track t = { 0, 0, NULL };
int node;
unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
sizeof(unsigned long), GFP_KERNEL);
if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
GFP_TEMPORARY))
if (!map || !alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
GFP_TEMPORARY)) {
kfree(map);
return sprintf(buf, "Out of memory\n");
}
/* Push back cpu slabs */
flush_all(s);
@ -3691,9 +3697,9 @@ static int list_locations(struct kmem_cache *s, char *buf,
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(page, &n->partial, lru)
process_slab(&t, s, page, alloc);
process_slab(&t, s, page, alloc, map);
list_for_each_entry(page, &n->full, lru)
process_slab(&t, s, page, alloc);
process_slab(&t, s, page, alloc, map);
spin_unlock_irqrestore(&n->list_lock, flags);
}
@ -3744,6 +3750,7 @@ static int list_locations(struct kmem_cache *s, char *buf,
}
free_loc_track(&t);
kfree(map);
if (!t.count)
len += sprintf(buf, "No data\n");
return len;