Commit e6e8379c authored Mar 25, 2016 by Alexander Potapenko Committed by Linus Torvalds Mar 25, 2016

kasan: modify kmalloc_large_oob_right(), add kmalloc_pagealloc_oob_right()



This patchset implements SLAB support for KASAN

Unlike SLUB, SLAB doesn't store allocation/deallocation stacks for heap
objects, therefore we reimplement this feature in mm/kasan/stackdepot.c.
The intention is to ultimately switch SLUB to use this implementation as
well, which will save a lot of memory (right now SLUB bloats each object
by 256 bytes to store the allocation/deallocation stacks).

Also neither SLUB nor SLAB delay the reuse of freed memory chunks, which
is necessary for better detection of use-after-free errors.  We
introduce memory quarantine (mm/kasan/quarantine.c), which allows
delayed reuse of deallocated memory.

This patch (of 7):

Rename kmalloc_large_oob_right() to kmalloc_pagealloc_oob_right(), as
the test only checks the page allocator functionality.  Also reimplement
kmalloc_large_oob_right() so that the test allocates a large enough
chunk of memory that still does not trigger the page allocator fallback.

Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent aaf4fb71

lib/test_kasan.c

+27 −1

Original line number	Diff line number	Diff line
		@@ -65,11 +65,34 @@ static noinline void __init kmalloc_node_oob_right(void)
		kfree(ptr);
		}

		static noinline void __init kmalloc_large_oob_right(void)
		#ifdef CONFIG_SLUB
		static noinline void __init kmalloc_pagealloc_oob_right(void)
		{
		char *ptr;
		size_t size = KMALLOC_MAX_CACHE_SIZE + 10;

		/* Allocate a chunk that does not fit into a SLUB cache to trigger
		* the page allocator fallback.
		*/
		pr_info("kmalloc pagealloc allocation: out-of-bounds to right\n");
		ptr = kmalloc(size, GFP_KERNEL);
		if (!ptr) {
		pr_err("Allocation failed\n");
		return;
		}

		ptr[size] = 0;
		kfree(ptr);
		}
		#endif

		static noinline void __init kmalloc_large_oob_right(void)
		{
		char *ptr;
		size_t size = KMALLOC_MAX_CACHE_SIZE - 256;
		/* Allocate a chunk that is large enough, but still fits into a slab
		* and does not trigger the page allocator fallback in SLUB.
		*/
		pr_info("kmalloc large allocation: out-of-bounds to right\n");
		ptr = kmalloc(size, GFP_KERNEL);
		if (!ptr) {
		@@ -324,6 +347,9 @@ static int __init kmalloc_tests_init(void)
		kmalloc_oob_right();
		kmalloc_oob_left();
		kmalloc_node_oob_right();
		#ifdef CONFIG_SLUB
		kmalloc_pagealloc_oob_right();
		#endif
		kmalloc_large_oob_right();
		kmalloc_oob_krealloc_more();
		kmalloc_oob_krealloc_less();

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