[PATCH 4.19 29/74] lib/test_overflow.c: avoid tainting the kernel and fix wrap size

From: Greg Kroah-Hartman
Date: Mon Aug 05 2019 - 09:13:01 EST

[ Upstream commit 8e060c21ae2c265a2b596e9e7f9f97ec274151a4 ]

This adds __GFP_NOWARN to the kmalloc()-portions of the overflow test to
avoid tainting the kernel. Additionally fixes up the math on wrap size
to be architecture and page size agnostic.

Link: http://lkml.kernel.org/r/201905282012.0A8767E24@keescook
Fixes: ca90800a91ba ("test_overflow: Add memory allocation overflow tests")
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Suggested-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
lib/test_overflow.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/lib/test_overflow.c b/lib/test_overflow.c
index fc680562d8b69..7a4b6f6c5473c 100644
--- a/lib/test_overflow.c
+++ b/lib/test_overflow.c
@@ -486,16 +486,17 @@ static int __init test_overflow_shift(void)
* Deal with the various forms of allocator arguments. See comments above
* the DEFINE_TEST_ALLOC() instances for mapping of the "bits".
-#define alloc010(alloc, arg, sz) alloc(sz, GFP_KERNEL)
-#define alloc011(alloc, arg, sz) alloc(sz, GFP_KERNEL, NUMA_NO_NODE)
+#define alloc_GFP (GFP_KERNEL | __GFP_NOWARN)
+#define alloc010(alloc, arg, sz) alloc(sz, alloc_GFP)
+#define alloc011(alloc, arg, sz) alloc(sz, alloc_GFP, NUMA_NO_NODE)
#define alloc000(alloc, arg, sz) alloc(sz)
#define alloc001(alloc, arg, sz) alloc(sz, NUMA_NO_NODE)
-#define alloc110(alloc, arg, sz) alloc(arg, sz, GFP_KERNEL)
+#define alloc110(alloc, arg, sz) alloc(arg, sz, alloc_GFP)
#define free0(free, arg, ptr) free(ptr)
#define free1(free, arg, ptr) free(arg, ptr)

-/* Wrap around to 8K */
-#define TEST_SIZE (9 << PAGE_SHIFT)
+/* Wrap around to 16K */
+#define TEST_SIZE (5 * 4096)

#define DEFINE_TEST_ALLOC(func, free_func, want_arg, want_gfp, want_node)\
static int __init test_ ## func (void *arg) \