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authorDmitry Vyukov <dvyukov@google.com>2018-02-06 15:36:23 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 18:32:42 -0800
commit47adccce3e8a31d315f47183ab1185862b2fc5d4 (patch)
treeaaf982ef67484b702b42440b459cfd648e58dc4e /lib/test_kasan.c
parentd321599cf6b861beefe92327476b617435c7fc4a (diff)
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/test_kasan.c')
-rw-r--r--lib/test_kasan.c33
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();