[PATCH] time: compat settimeofday: Validate the values of tv from user

[zhengbin]

Similar to commit 6ada1fc0e1c4
("time: settimeofday: Validate the values of tv from user"),
an unvalidated user input is multiplied by a constant, which can result
in an undefined behaviour for large values. While this is validated
later, we should avoid triggering undefined behaviour.

Signed-off-by: zhengbin <zhengbin13@xxxxxxxxxx>
---
 kernel/time/time.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/time/time.c b/kernel/time/time.c
index 7f7d691..5c54ca6 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -251,6 +251,10 @@ COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
 	if (tv) {
 		if (compat_get_timeval(&user_tv, tv))
 			return -EFAULT;
+
+		if (!timeval_valid(&user_tv))
+			return -EINVAL;
+
 		new_ts.tv_sec = user_tv.tv_sec;
 		new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
 	}
--
2.7.4