mm: mempool: kasan: don't poot mempool objects in quarantine
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: 55834c59098d ("mm: kasan: initial memory quarantine implementation")
Link: http://lkml.kernel.org/r/575977C3.1010905@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mempool.c b/mm/mempool.c
index 9e075f8..8f65464 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -104,20 +104,16 @@
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);
}