linux-kernel - [PATCH] hams: Fix deadlock caused by unsafe-irq lock in sp

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Date: Fri, 19 Apr 2024 02:30:37 +0900
From: Jeongjun Park <aha310510@...il.com>
To: ajk@...nets.uni-bremen.de
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	linux-hams@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	syzkaller-bugs@...glegroups.com,
	syzbot+8e03da5d64bc85098811@...kaller.appspotmail.com,
	Jeongjun Park <aha310510@...il.com>
Subject: [PATCH] hams: Fix deadlock caused by unsafe-irq lock in sp_get()


read_lock() present in sp_get() is interrupt-vulnerable, so the function needs to be modified.


Reported-by: syzbot+8e03da5d64bc85098811@...kaller.appspotmail.com
Signed-off-by: Jeongjun Park <aha310510@...il.com>
---
 drivers/net/hamradio/6pack.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index 6ed38a3cdd73..f882682ff0c8 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c
@@ -372,12 +372,13 @@ static DEFINE_RWLOCK(disc_data_lock);
 static struct sixpack *sp_get(struct tty_struct *tty)
 {
 	struct sixpack *sp;
+	unsigned long flags;
 
-	read_lock(&disc_data_lock);
+	flags = read_lock_irqsave(&disc_data_lock);
 	sp = tty->disc_data;
 	if (sp)
 		refcount_inc(&sp->refcnt);
-	read_unlock(&disc_data_lock);
+	read_unlock_irqrestore(&disc_data_lock, flags);
 
 	return sp;
 }
-- 
2.34.1