Commit 9dd5134c authored by Kees Cook's avatar Kees Cook
Browse files

kunit/overflow: Adjust for __counted_by with DEFINE_RAW_FLEX() 



When a flexible array structure has a __counted_by annotation, its use
with DEFINE_RAW_FLEX() will result in the count being zero-initialized.
This is expected since one doesn't want to use RAW with a counted_by
struct. Adjust the tests to check for the condition and for compiler
support.

Reported-by: default avatarChristian Schrefl <chrisi.schrefl@gmail.com>
Closes: https://lore.kernel.org/all/0bfc6b38-8bc5-4971-b6fb-dc642a73fbfe@gmail.com/


Suggested-by: default avatarNathan Chancellor <nathan@kernel.org>
Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20240610182301.work.272-kees@kernel.org


Tested-by: default avatarChristian Schrefl <chrisi.schrefl@gmail.com>
Reviewed-by: default avatarChristian Schrefl <chrisi.schrefl@gmail.com>
Signed-off-by: default avatarKees Cook <kees@kernel.org>
parent f7d3b1ff

lib/overflow_kunit.c

+17 −3
Original line number Diff line number Diff line
@@ -1178,14 +1178,28 @@ struct foo { 
	s16 array[] __counted_by(counter);

};



struct bar {

	int a;

	u32 counter;

	s16 array[];

};



static void DEFINE_FLEX_test(struct kunit *test)

{

	DEFINE_RAW_FLEX(struct foo, two, array, 2);

	/* Using _RAW_ on a __counted_by struct will initialize "counter" to zero */

	DEFINE_RAW_FLEX(struct foo, two_but_zero, array, 2);

#if __has_attribute(__counted_by__)

	int expected_raw_size = sizeof(struct foo);

#else

	int expected_raw_size = sizeof(struct foo) + 2 * sizeof(s16);

#endif

	/* Without annotation, it will always be on-stack size. */

	DEFINE_RAW_FLEX(struct bar, two, array, 2);

	DEFINE_FLEX(struct foo, eight, array, counter, 8);

	DEFINE_FLEX(struct foo, empty, array, counter, 0);



	KUNIT_EXPECT_EQ(test, __struct_size(two),

			sizeof(struct foo) + sizeof(s16) + sizeof(s16));

	KUNIT_EXPECT_EQ(test, __struct_size(two_but_zero), expected_raw_size);

	KUNIT_EXPECT_EQ(test, __struct_size(two), sizeof(struct bar) + 2 * sizeof(s16));

	KUNIT_EXPECT_EQ(test, __struct_size(eight), 24);

	KUNIT_EXPECT_EQ(test, __struct_size(empty), sizeof(struct foo));

}