linux-kernel - Re: [syzbot] possible deadlock in input

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Date: Sat, 20 Apr 2024 01:33:49 +0900
From: Jeongjun Park <aha310510@...il.com>
To: syzbot+d4c06e848a1c1f9f726f@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] possible deadlock in input_event (2)


please test deadlock in input_event

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

---
 fs/fcntl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 54cc85d3338e..30f4d75fdb03 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -829,7 +829,7 @@ int send_sigurg(struct fown_struct *fown)
 	struct task_struct *p;
 	enum pid_type type;
 	struct pid *pid;
-	unsigned long flags;
+	unsigned long flags, read_flags;
 	int ret = 0;
 	
 	read_lock_irqsave(&fown->lock, flags);
@@ -848,11 +848,11 @@ int send_sigurg(struct fown_struct *fown)
 			send_sigurg_to_task(p, fown, type);
 		rcu_read_unlock();
 	} else {
-		read_lock(&tasklist_lock);
+		read_lock_irqsave(&tasklist_lock, read_flags);
 		do_each_pid_task(pid, type, p) {
 			send_sigurg_to_task(p, fown, type);
 		} while_each_pid_task(pid, type, p);
-		read_unlock(&tasklist_lock);
+		read_unlock_irqrestore(&tasklist_lock, read_flags);
 	}
  out_unlock_fown:
 	read_unlock_irqrestore(&fown->lock, flags);
-- 
2.34.1