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mm: mempool: kasan: don't poot mempool objects in quarantine

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Currently we may put reserved by mempool elements into quarantine via
kasan_kfree().  This is totally wrong since quarantine may really free
these objects.  So when mempool will try to use such element,
use-after-free will happen.  Or mempool may decide that it no longer
need that element and double-free it.

So don't put object into quarantine in kasan_kfree(), just poison it.
Rename kasan_kfree() to kasan_poison_kfree() to respect that.

Also, we shouldn't use kasan_slab_alloc()/kasan_krealloc() in
kasan_unpoison_element() because those functions may update allocation
stacktrace.  This would be wrong for the most of the remove_element call
sites.

(The only call site where we may want to update alloc stacktrace is
 in mempool_alloc(). Kmemleak solves this by calling
 kmemleak_update_trace(), so we could make something like that too.
 But this is out of scope of this patch).

Fixes: 55834c5909 ("mm: kasan: initial memory quarantine implementation")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Andrey Ryabinin <[email protected]>
Reported-by: Kuthonuzo Luruo <[email protected]>
Acked-by: Alexander Potapenko <[email protected]>
Cc: Dmitriy Vyukov <[email protected]>
Cc: Kostya Serebryany <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Andrey Ryabinin 2016-06-24 14:49:34 -07:00 • committed by Linus Torvalds
commit 9b75a867cc
3 changed files with 14 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

12
mm/mempool.c
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@ -104,20 +104,16 @@ static inline void poison_element(mempool_t *pool, void *element)
static void kasan_poison_element(mempool_t *pool, void *element)
{
if (pool->alloc == mempool_alloc_slab)
kasan_poison_slab_free(pool->pool_data, element);
if (pool->alloc == mempool_kmalloc)
kasan_kfree(element);
if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
kasan_poison_kfree(element);
if (pool->alloc == mempool_alloc_pages)
kasan_free_pages(element, (unsigned long)pool->pool_data);
}
static void kasan_unpoison_element(mempool_t *pool, void *element, gfp_t flags)
{
if (pool->alloc == mempool_alloc_slab)
kasan_slab_alloc(pool->pool_data, element, flags);
if (pool->alloc == mempool_kmalloc)
kasan_krealloc(element, (size_t)pool->pool_data, flags);
if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
kasan_unpoison_slab(element);
if (pool->alloc == mempool_alloc_pages)
kasan_alloc_pages(element, (unsigned long)pool->pool_data);
}