[PATCH] time/namespace: Validate nanosecond field in proc_timens_set_offset()

[Malaya Kumar Rout <malayarout91@gmail.com>]

The function validates tv_sec to be within [-KTIME_SEC_MAX, KTIME_SEC_MAX]
but never validates that tv_nsec is within the valid range of
[0, NSEC_PER_SEC-1] before using it in timespec64_add().

timespec64_add() expects both timespec64 structures to have normalized
values with tv_nsec in the range [0, 999999999]. If off->val.tv_nsec
contains invalid values (negative or >= NSEC_PER_SEC), it could lead to
incorrect calculations or unexpected behavior.

Add validation to ensure tv_nsec is within the valid range before
performing the addition.

Fixes: 04a8682a71be ("fs/proc: Introduce /proc/pid/timens_offsets")
Signed-off-by: Malaya Kumar Rout <malayarout91@gmail.com>
---
 kernel/time/namespace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 5fa0af66cf3f..d1b5de88f8ff 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -297,6 +297,9 @@ int proc_timens_set_offset(struct file *file, struct task_struct *p,
 		    off->val.tv_sec < -KTIME_SEC_MAX)
 			return -ERANGE;
 
+		if (off->val.tv_nsec < 0 || off->val.tv_nsec >= NSEC_PER_SEC)
+			return -EINVAL;
+
 		tp = timespec64_add(tp, off->val);
 		/*
 		 * KTIME_SEC_MAX is divided by 2 to be sure that KTIME_MAX is
-- 
2.54.0