From: Siddh Raman Pant via Linux-kernel-mentees <linux-kernel-mentees@lists.linuxfoundation.org>
To: David Howells <dhowells@redhat.com>,
Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
Eric Dumazet <edumazet@google.com>,
"Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: linux-security-modules <linux-security-module@vger.kernel.org>,
linux-kernel-mentees
<linux-kernel-mentees@lists.linuxfoundation.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com
Subject: [PATCH] kernel/watch_queue: Make pipe NULL while clearing watch_queue
Date: Sat, 23 Jul 2022 19:24:47 +0530 [thread overview]
Message-ID: <20220723135447.199557-1-code@siddh.me> (raw)
If not done, a reference to a freed pipe remains in the watch_queue,
as this function is called before freeing a pipe in free_pipe_info()
(see line 834 of fs/pipe.c).
This causes a UAF when post_one_notification tries to access the pipe on
a key update, which is reported by syzbot.
Bug report: https://syzkaller.appspot.com/bug?id=1870dd7791ba05f2ea7f47f7cbdde701173973fc
Reported-and-tested-by: syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com
Signed-off-by: Siddh Raman Pant <code@siddh.me>
---
kernel/watch_queue.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index bb9962b33f95..bab9e09c74cf 100644
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -637,8 +637,17 @@ void watch_queue_clear(struct watch_queue *wqueue)
spin_lock_bh(&wqueue->lock);
}
- spin_unlock_bh(&wqueue->lock);
rcu_read_unlock();
+
+ /* Clearing the watch queue, so we should clean the associated pipe. */
+#ifdef CONFIG_WATCH_QUEUE
+ if (wqueue->pipe) {
+ wqueue->pipe->watch_queue = NULL;
+ wqueue->pipe = NULL;
+ }
+#endif
+
+ spin_unlock_bh(&wqueue->lock);
}
/**
--
2.35.1
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next reply other threads:[~2022-07-23 13:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-23 13:54 Siddh Raman Pant via Linux-kernel-mentees [this message]
2022-07-23 14:03 ` [PATCH] kernel/watch_queue: Make pipe NULL while clearing watch_queue Greg KH
2022-07-23 14:29 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-24 3:45 ` Khalid Masum
2022-07-24 4:02 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-23 14:04 ` Greg KH
2022-07-23 14:29 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-27 14:46 ` David Howells
2022-07-27 16:20 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-31 18:11 ` Dipanjan Das
2022-07-31 18:46 ` Siddh Raman Pant via Linux-kernel-mentees
2022-08-01 8:47 ` Greg KH
2022-08-01 8:53 ` Siddh Raman Pant via Linux-kernel-mentees
2022-07-27 14:15 ` David Howells
2022-07-27 14:23 ` Siddh Raman Pant via Linux-kernel-mentees
[not found] <20220801121513.28E4B5204D1@webmail.sinamail.sina.com.cn>
2022-08-01 12:52 ` Siddh Raman Pant via Linux-kernel-mentees
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