linux-kernel - Re: [syzbot] [netfs?] WARNING: refcount bug in netfs_put

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Message-ID: <20250214111926.2252-1-hdanton@sina.com>
Date: Fri, 14 Feb 2025 19:19:25 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+d9890527385ab9767e03@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [netfs?] WARNING: refcount bug in netfs_put_subrequest

On Thu, 13 Feb 2025 22:39:25 -0800
> syzbot found the following issue on:
> 
> HEAD commit:    69b54314c975 Merge tag 'kbuild-fixes-v6.14' of git://git.k..
> git tree:       upstream
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13aafdf8580000

#syz test upstream   master

--- x/fs/netfs/read_collect.c
+++ y/fs/netfs/read_collect.c
@@ -289,6 +289,10 @@ reassess:
 		/* Remove if completely consumed. */
 		stream->source = front->source;
 		spin_lock(&rreq->lock);
+		if (front != stream->front) {
+			spin_unlock(&rreq->lock);
+			goto reassess;
+		}
 
 		remove = front;
 		trace_netfs_sreq(front, netfs_sreq_trace_discard);
--