UPSTREAM: kasan: add tests for alloca poisoning

Link: http://lkml.kernel.org/r/20171204191735.132544-5-paullawrence@google.com
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

(cherry-picked from 00a14294bb33af533f7ac002fb20623fdd8ea0d7)
Change-Id: I2c3b607d67b4a788000c62ce920cfd603f42fa06
Signed-off-by: Paul Lawrence <paullawrence@google.com>
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 0e70ecc..8fcad61 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -440,6 +440,26 @@
 	p[1023] = 1;
 }
 
+static noinline void __init kasan_alloca_oob_left(void)
+{
+	volatile int i = 10;
+	char alloca_array[i];
+	char *p = alloca_array - 1;
+
+	pr_info("out-of-bounds to left on alloca\n");
+	*(volatile char *)p;
+}
+
+static noinline void __init kasan_alloca_oob_right(void)
+{
+	volatile int i = 10;
+	char alloca_array[i];
+	char *p = alloca_array + i;
+
+	pr_info("out-of-bounds to right on alloca\n");
+	*(volatile char *)p;
+}
+
 static int __init kmalloc_tests_init(void)
 {
 	/*
@@ -469,6 +489,8 @@
 	kmem_cache_oob();
 	kasan_stack_oob();
 	kasan_global_oob();
+	kasan_alloca_oob_left();
+	kasan_alloca_oob_right();
 	ksize_unpoisons_memory();
 	copy_user_test();
 	use_after_scope_test();