Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.
As recommended[2] by[3] Linus[4], remove the macro. With the recent
change to disable -Wmaybe-uninitialized in v5.7 in commit
78a5255ffb6a
("Stop the ad-hoc games with -Wno-maybe-initialized"), this is likely
the best time to make this treewide change.
[1] https://lore.kernel.org/lkml/
20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Bart van Assche <bvanassche@acm.org>
Reviewed-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
/* Compiler specific definitions for Clang compiler */
-#define uninitialized_var(x) x = *(&(x))
-
/* same as gcc, this was present in clang-2.6 so we can assume it works
* with any version that can compile the kernel
*/
(typeof(ptr)) (__ptr + (off)); \
})
-/*
- * A trick to suppress uninitialized variable warning without generating any
- * code
- */
-#define uninitialized_var(x) x = x
-
#ifdef CONFIG_RETPOLINE
#define __noretpoline __attribute__((__indirect_branch__("keep")))
#endif
# define noinline
#endif
-#define uninitialized_var(x) x = *(&(x))
-
#include <linux/types.h>
/*
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
-#define uninitialized_var(x) x = x
-
# ifndef likely
# define likely(x) (__builtin_expect(!!(x), 1))
# endif