From e6e8379c876de16c6b78f83b15d5ac32c79cb440 Mon Sep 17 00:00:00 2001 From: Alexander Potapenko Date: Fri, 25 Mar 2016 14:21:56 -0700 Subject: 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 Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Steven Rostedt Cc: Konstantin Serebryany Cc: Dmitry Chernenkov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index c32f3b0048dc..90ad74f71535 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -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(); -- cgit v1.2.3 From 9dcadd381b1d199074937019d612346c061de415 Mon Sep 17 00:00:00 2001 From: Alexander Potapenko Date: Fri, 25 Mar 2016 14:22:11 -0700 Subject: kasan: test fix: warn if the UAF could not be detected in kmalloc_uaf2 Signed-off-by: Alexander Potapenko Acked-by: Andrey Ryabinin Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Steven Rostedt Cc: Konstantin Serebryany Cc: Dmitry Chernenkov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 90ad74f71535..82169fbf2453 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -294,6 +294,8 @@ static noinline void __init kmalloc_uaf2(void) } ptr1[40] = 'x'; + if (ptr1 == ptr2) + pr_err("Could not detect use-after-free: ptr1 == ptr2\n"); kfree(ptr2); } -- cgit v1.2.3