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author | Dmitry Vyukov <dvyukov@google.com> | 2018-02-06 15:36:23 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-02-06 18:32:42 -0800 |
commit | 47adccce3e8a31d315f47183ab1185862b2fc5d4 (patch) | |
tree | aaf982ef67484b702b42440b459cfd648e58dc4e /lib | |
parent | d321599cf6b861beefe92327476b617435c7fc4a (diff) | |
download | linux-47adccce3e8a31d315f47183ab1185862b2fc5d4.tar.gz linux-47adccce3e8a31d315f47183ab1185862b2fc5d4.tar.bz2 linux-47adccce3e8a31d315f47183ab1185862b2fc5d4.zip |
kasan: detect invalid frees for large objects
Patch series "kasan: detect invalid frees".
KASAN detects double-frees, but does not detect invalid-frees (when a
pointer into a middle of heap object is passed to free). We recently had
a very unpleasant case in crypto code which freed an inner object inside
of a heap allocation. This left unnoticed during free, but totally
corrupted heap and later lead to a bunch of random crashes all over kernel
code.
Detect invalid frees.
This patch (of 5):
Detect frees of pointers into middle of large heap objects.
I dropped const from kasan_kfree_large() because it starts propagating
through a bunch of functions in kasan_report.c, slab/slub nearest_obj(),
all of their local variables, fixup_red_left(), etc.
Link: http://lkml.kernel.org/r/1b45b4fe1d20fc0de1329aab674c1dd973fee723.1514378558.git.dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/test_kasan.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 2724f86c4cef..e9c5d765be66 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -94,6 +94,37 @@ static noinline void __init kmalloc_pagealloc_oob_right(void) ptr[size] = 0; kfree(ptr); } + +static noinline void __init kmalloc_pagealloc_uaf(void) +{ + char *ptr; + size_t size = KMALLOC_MAX_CACHE_SIZE + 10; + + pr_info("kmalloc pagealloc allocation: use-after-free\n"); + ptr = kmalloc(size, GFP_KERNEL); + if (!ptr) { + pr_err("Allocation failed\n"); + return; + } + + kfree(ptr); + ptr[0] = 0; +} + +static noinline void __init kmalloc_pagealloc_invalid_free(void) +{ + char *ptr; + size_t size = KMALLOC_MAX_CACHE_SIZE + 10; + + pr_info("kmalloc pagealloc allocation: invalid-free\n"); + ptr = kmalloc(size, GFP_KERNEL); + if (!ptr) { + pr_err("Allocation failed\n"); + return; + } + + kfree(ptr + 1); +} #endif static noinline void __init kmalloc_large_oob_right(void) @@ -505,6 +536,8 @@ static int __init kmalloc_tests_init(void) kmalloc_node_oob_right(); #ifdef CONFIG_SLUB kmalloc_pagealloc_oob_right(); + kmalloc_pagealloc_uaf(); + kmalloc_pagealloc_invalid_free(); #endif kmalloc_large_oob_right(); kmalloc_oob_krealloc_more(); |