From: Alexander Potapenko <glider@google.com>
Date: Fri, 25 Mar 2016 21:21:56 +0000 (-0700)
Subject: kasan: modify kmalloc_large_oob_right(), add kmalloc_pagealloc_oob_right()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=e6e8379c876de16c6b78f83b15d5ac32c79cb440;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

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>
---

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();