[PATCH] time: Fix off-by-one in compat settimeofday() usec validation

[Wang Yan]

The compat version of settimeofday() uses '>' instead of '>=' when
validating tv_usec against USEC_PER_SEC, allowing the value 1000000
to pass the check. After the subsequent conversion to nanoseconds
(tv_nsec *= NSEC_PER_USEC), this results in tv_nsec == NSEC_PER_SEC,
which violates the timespec invariant that tv_nsec must be strictly
less than NSEC_PER_SEC.

The native settimeofday() was already fixed in commit ce4abda5e126
("time: Fix off-by-one in settimeofday() usec validation"), but the
compat counterpart was missed.

Fix it by using '>=' to reject tv_usec values outside the valid
range [0, USEC_PER_SEC - 1].

Fixes: 5e0fb1b57bea ("y2038: time: avoid timespec usage in settimeofday()")
Signed-off-by: Wang Yan <wangyan01@xxxxxxxxxx>
---
 kernel/time/time.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/time.c b/kernel/time/time.c
index 771cef87ad3b..0dd63a91e7c5 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -251,7 +251,7 @@ COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
 		    get_user(new_ts.tv_nsec, &tv->tv_usec))
 			return -EFAULT;
 
-		if (new_ts.tv_nsec > USEC_PER_SEC || new_ts.tv_nsec < 0)
+		if (new_ts.tv_nsec >= USEC_PER_SEC || new_ts.tv_nsec < 0)
 			return -EINVAL;
 
 		new_ts.tv_nsec *= NSEC_PER_USEC;
-- 
2.25.1