y2038: time: avoid timespec usage in settimeofday()

The compat_get_timeval() and timeval_valid() interfaces are deprecated
and getting removed along with the definition of struct timeval itself.

Change the two implementations of the settimeofday() system call to
open-code these helpers and completely avoid references to timeval.

The timeval_valid() call is not needed any more here, only a check to
avoid overflowing tv_nsec during the multiplication, as there is another
range check in do_sys_settimeofday64().

Tested-by: syzbot+dccce9b26ba09ca49966@syzkaller.appspotmail.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

include/linux/syscalls.h

@@ -734,7 +734,7 @@ asmlinkage long sys_getcpu(unsigned __user *cpu, unsigned __user *node, struct g
 /* kernel/time.c */
 asmlinkage long sys_gettimeofday(struct __kernel_old_timeval __user *tv,
 				struct timezone __user *tz);
-asmlinkage long sys_settimeofday(struct timeval __user *tv,
+asmlinkage long sys_settimeofday(struct __kernel_old_timeval __user *tv,
 				struct timezone __user *tz);
 asmlinkage long sys_adjtimex(struct __kernel_timex __user *txc_p);
 asmlinkage long sys_adjtimex_time32(struct old_timex32 __user *txc_p);

kernel/time/time.c

@@ -196,22 +196,21 @@ int do_sys_settimeofday64(const struct timespec64 *tv, const struct timezone *tz
 	return 0;
 }
 
-SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
+SYSCALL_DEFINE2(settimeofday, struct __kernel_old_timeval __user *, tv,
 		struct timezone __user *, tz)
 {
 	struct timespec64 new_ts;
-	struct timeval user_tv;
 	struct timezone new_tz;
 
 	if (tv) {
-		if (copy_from_user(&user_tv, tv, sizeof(*tv)))
+		if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
+		    get_user(new_ts.tv_nsec, &tv->tv_usec))
 			return -EFAULT;
 
-		if (!timeval_valid(&user_tv))
+		if (new_ts.tv_nsec > USEC_PER_SEC || new_ts.tv_nsec < 0)
 			return -EINVAL;
 
-		new_ts.tv_sec = user_tv.tv_sec;
-		new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
+		new_ts.tv_nsec *= NSEC_PER_USEC;
 	}
 	if (tz) {
 		if (copy_from_user(&new_tz, tz, sizeof(*tz)))
@@ -245,18 +244,17 @@ COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
 		       struct timezone __user *, tz)
 {
 	struct timespec64 new_ts;
-	struct timeval user_tv;
 	struct timezone new_tz;
 
 	if (tv) {
-		if (compat_get_timeval(&user_tv, tv))
+		if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
+		    get_user(new_ts.tv_nsec, &tv->tv_usec))
 			return -EFAULT;
 
-		if (!timeval_valid(&user_tv))
+		if (new_ts.tv_nsec > USEC_PER_SEC || new_ts.tv_nsec < 0)
 			return -EINVAL;
 
-		new_ts.tv_sec = user_tv.tv_sec;
-		new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
+		new_ts.tv_nsec *= NSEC_PER_USEC;
 	}
 	if (tz) {
 		if (copy_from_user(&new_tz, tz, sizeof(*tz)))