netdev - [PATCH v2] netdevsim: Add trailing zero to terminate the string in nsim_nexthop_bucket_activity

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Message-Id: <20241022171907.8606-1-zichenxie0106@gmail.com>
Date: Tue, 22 Oct 2024 12:19:08 -0500
From: Gax-c <zichenxie0106@...il.com>
To: kuba@...nel.org,
	andrew+netdev@...n.ch,
	davem@...emloft.net,
	edumazet@...gle.com,
	pabeni@...hat.com,
	petrm@...dia.com,
	idosch@...dia.com
Cc: netdev@...r.kernel.org,
	zzjas98@...il.com,
	chenyuan0y@...il.com,
	Zichen Xie <zichenxie0106@...il.com>
Subject: [PATCH v2] netdevsim: Add trailing zero to terminate the string in nsim_nexthop_bucket_activity_write()

From: Zichen Xie <zichenxie0106@...il.com>

This was found by a static analyzer.
We should not forget the trailing zero after copy_from_user()
if we will further do some string operations, sscanf() in this
case. Adding a trailing zero will ensure that the function
performs properly.

Fixes: c6385c0b67c5 ("netdevsim: Allow reporting activity on nexthop buckets")
Signed-off-by: Zichen Xie <zichenxie0106@...il.com>
---
v2: adjust code format.
---
 drivers/net/netdevsim/fib.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/netdevsim/fib.c b/drivers/net/netdevsim/fib.c
index 41e80f78b316..16c382c42227 100644
--- a/drivers/net/netdevsim/fib.c
+++ b/drivers/net/netdevsim/fib.c
@@ -1377,10 +1377,12 @@ static ssize_t nsim_nexthop_bucket_activity_write(struct file *file,
 
 	if (pos != 0)
 		return -EINVAL;
-	if (size > sizeof(buf))
+	if (size > sizeof(buf) - 1)
 		return -EINVAL;
 	if (copy_from_user(buf, user_buf, size))
 		return -EFAULT;
+	buf[size] = 0;
+
 	if (sscanf(buf, "%u %hu", &nhid, &bucket_index) != 2)
 		return -EINVAL;
 
-- 
2.34.1