netdev - [PATCH net] netdevsim: prevent bad user input in nsim_dev_health_break

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Message-ID: <20241213172518.2415666-1-edumazet@google.com>
Date: Fri, 13 Dec 2024 17:25:18 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, Simon Horman <horms@...nel.org>, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, syzbot+ea40e4294e58b0292f74@...kaller.appspotmail.com, 
	Jiri Pirko <jiri@...dia.com>
Subject: [PATCH net] netdevsim: prevent bad user input in nsim_dev_health_break_write()

If either a zero count or a large one is provided, kernel can crash.

Fixes: 82c93a87bf8b ("netdevsim: implement couple of testing devlink health reporters")
Reported-by: syzbot+ea40e4294e58b0292f74@...kaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/675c6862.050a0220.37aaf.00b1.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Jiri Pirko <jiri@...dia.com>
---
 drivers/net/netdevsim/health.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/netdevsim/health.c b/drivers/net/netdevsim/health.c
index 70e8bdf34be900f744e821fb237641a27bb71a7b..688f05316b5e109fc84222476023f3f1f078cf28 100644
--- a/drivers/net/netdevsim/health.c
+++ b/drivers/net/netdevsim/health.c
@@ -149,6 +149,8 @@ static ssize_t nsim_dev_health_break_write(struct file *file,
 	char *break_msg;
 	int err;
 
+	if (count == 0 || count > PAGE_SIZE)
+		return -EINVAL;
 	break_msg = memdup_user_nul(data, count);
 	if (IS_ERR(break_msg))
 		return PTR_ERR(break_msg);
-- 
2.47.1.613.gc27f4b7a9f-goog