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authorEric Dumazet <eric.dumazet@gmail.com>2010-03-24 22:25:47 +0100
committerPekka Enberg <penberg@cs.helsinki.fi>2010-05-22 10:57:30 +0300
commitbbd7d57bfe852d9788bae5fb171c7edb4021d8ac (patch)
tree9b16ed244e0bd0b71a1d3d6e662be310f1e8f9c2 /mm/slub.c
parente40152ee1e1c7a63f4777791863215e3faa37a86 (diff)
downloadlinux-bbd7d57bfe852d9788bae5fb171c7edb4021d8ac.tar.bz2
slub: Potential stack overflow
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>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c25
1 files changed, 16 insertions, 9 deletions
diff --git a/mm/slub.c b/mm/slub.c
index d2a54fe71ea2..78f1a202ca33 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -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;