include, lib: add __printf attributes to several function prototypes

Using __printf attributes helps to detect several format string issues
at compile time (even though -Wformat-security is currently disabled in
Makefile).  For example it can detect when formatting a pointer as a
number, like the issue fixed in commit a3fa71c40f18 ("wl18xx: show
rx_frames_per_rates as an array as it really is"), or when the arguments
do not match the format string, c.f.  for example commit 5ce1aca81435
("reiserfs: fix __RASSERT format string").

To prevent similar bugs in the future, add a __printf attribute to every
function prototype which needs one in include/linux/ and lib/.  These
functions were mostly found by using gcc's -Wsuggest-attribute=format
flag.

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/compat.h b/include/linux/compat.h
index ab25814690bc..a76c9172b2eb 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -424,7 +424,7 @@ asmlinkage long compat_sys_settimeofday(struct compat_timeval __user *tv,
 
 asmlinkage long compat_sys_adjtimex(struct compat_timex __user *utp);
 
-extern int compat_printk(const char *fmt, ...);
+extern __printf(1, 2) int compat_printk(const char *fmt, ...);
 extern void sigset_from_compat(sigset_t *set, const compat_sigset_t *compat);
 extern void sigset_to_compat(compat_sigset_t *compat, const sigset_t *set);