All fake flexible arrays should have been removed now, so remove the
special casing that was avoiding checking them. If a destination claims
to be 0 sized, believe it. This is especially important for cases where
__counted_by is in use and may have a 0 element count.
Signed-off-by: Kees Cook <k...@kernel.org>
---
include/linux/fortify-string.h | 8 ++------
lib/fortify_kunit.c | 3 +--
2 files changed, 3 insertions(+), 8 deletions(-)
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index 7e0f340bf363..0d99bf11d260 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -601,11 +601,7 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t
size,
/*
* Warn when writing beyond destination field size.
*
- * We must ignore p_size_field == 0 for existing 0-element
- * fake flexible arrays, until they are all converted to
- * proper flexible arrays.
- *
- * The implementation of __builtin_*object_size() behaves
+ * Note the implementation of __builtin_*object_size() behaves
* like sizeof() when not directly referencing a flexible
* array member, which means there will be many bounds checks
* that will appear at run-time, without a way for them to be
@@ -613,7 +609,7 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t
size,
* is specifically the flexible array member).
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832
*/
- if (p_size_field != 0 && p_size_field != SIZE_MAX &&
+ if (p_size_field != SIZE_MAX &&
p_size != p_size_field && p_size_field < size)
return true;
diff --git a/lib/fortify_kunit.c b/lib/fortify_kunit.c
index f9cc467334ce..f0c64b9e9b46 100644
--- a/lib/fortify_kunit.c
+++ b/lib/fortify_kunit.c
@@ -910,10 +910,9 @@ static void fortify_test_##memfunc(struct kunit *test)
\
memfunc(zero.buf, srcB, 0 + unconst); \
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); \
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); \
- /* We currently explicitly ignore zero-sized dests. */ \
memfunc(zero.buf, srcB, 1 + unconst); \
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); \
- KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); \
+ KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1); \
}
__fortify_test(memcpy)
__fortify_test(memmove)
--
2.34.1
