6.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook keescook@chromium.org
[ Upstream commit 74df22453c51392476117d7330bf02cee6e987cf ]
The __alloc_size annotation for kmemdup() was getting disabled under KUnit testing because the replaced fortify_panic macro implementation was using "return NULL" as a way to survive the sanity checking. But having the chance to return NULL invalidated __alloc_size, so kmemdup was not passing the __builtin_dynamic_object_size() tests any more:
[23:26:18] [PASSED] fortify_test_alloc_size_kmalloc_const [23:26:19] # fortify_test_alloc_size_kmalloc_dynamic: EXPECTATION FAILED at lib/fortify_kunit.c:265 [23:26:19] Expected __builtin_dynamic_object_size(p, 1) == expected, but [23:26:19] __builtin_dynamic_object_size(p, 1) == -1 (0xffffffffffffffff) [23:26:19] expected == 11 (0xb) [23:26:19] __alloc_size() not working with __bdos on kmemdup("hello there", len, gfp) [23:26:19] [FAILED] fortify_test_alloc_size_kmalloc_dynamic
Normal builds were not affected: __alloc_size continued to work there.
Use a zero-sized allocation instead, which allows __alloc_size to behave.
Fixes: 4ce615e798a7 ("fortify: Provide KUnit counters for failure testing") Fixes: fa4a3f86d498 ("fortify: Add KUnit tests for runtime overflows") Link: https://lore.kernel.org/r/20240501232937.work.532-kees@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/fortify-string.h | 3 ++- lib/fortify_kunit.c | 6 +++--- 2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h index 6aeebe0a67770..6eaa190d0083c 100644 --- a/include/linux/fortify-string.h +++ b/include/linux/fortify-string.h @@ -734,7 +734,8 @@ __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp if (__compiletime_lessthan(p_size, size)) __read_overflow(); if (p_size < size) - fortify_panic(FORTIFY_FUNC_kmemdup, FORTIFY_READ, p_size, size, NULL); + fortify_panic(FORTIFY_FUNC_kmemdup, FORTIFY_READ, p_size, size, + __real_kmemdup(p, 0, gfp)); return __real_kmemdup(p, size, gfp); }
diff --git a/lib/fortify_kunit.c b/lib/fortify_kunit.c index 86c1b1a6e2c89..fdba0eaf19a59 100644 --- a/lib/fortify_kunit.c +++ b/lib/fortify_kunit.c @@ -917,19 +917,19 @@ static void kmemdup_test(struct kunit *test)
/* Out of bounds by 1 byte. */ copy = kmemdup(src, len + 1, GFP_KERNEL); - KUNIT_EXPECT_NULL(test, copy); + KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR); KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); kfree(copy);
/* Way out of bounds. */ copy = kmemdup(src, len * 2, GFP_KERNEL); - KUNIT_EXPECT_NULL(test, copy); + KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR); KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); kfree(copy);
/* Starting offset causing out of bounds. */ copy = kmemdup(src + 1, len, GFP_KERNEL); - KUNIT_EXPECT_NULL(test, copy); + KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR); KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3); kfree(copy); }