From: Pavel Skripkin <paskripkin@gmail.com>
To: ralf@linux-mips.org, davem@davemloft.net, kuba@kernel.org
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: GPF in net sybsystem
Date: Wed, 5 May 2021 20:02:42 +0300 [thread overview]
Message-ID: <20210505200242.31d58452@gmail.com> (raw)
Hi, netdev developers!
I've spent some time debugging this bug
https://syzkaller.appspot.com/bug?id=c670fb9da2ce08f7b5101baa9426083b39ee9f90
and, I believe, I found the root case:
static int nr_accept(struct socket *sock, struct socket *newsock, int flags,
bool kern)
{
....
for (;;) {
prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
...
if (!signal_pending(current)) {
release_sock(sk);
schedule();
lock_sock(sk);
continue;
}
...
}
...
}
When calling process will be scheduled, another proccess can release
this socket and set sk->sk_wq to NULL. (In this case nr_release()
will call sock_orphan(sk)). In this case GPF will happen in
prepare_to_wait().
I came up with this patch, but im not an expect in netdev sybsystem and
im not sure about this one:
diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
index 6d16e1ab1a8a..89ceddea48e8 100644
--- a/net/netrom/af_netrom.c
+++ b/net/netrom/af_netrom.c
@@ -803,6 +803,10 @@ static int nr_accept(struct socket *sock, struct socket *newsock, int flags,
release_sock(sk);
schedule();
lock_sock(sk);
+ if (sock_flag(sk, SOCK_DEAD)) {
+ err = -ECONNABORTED;
+ goto out_release;
+ }
continue;
}
err = -ERESTARTSYS;
I look forward to hearing your perspective on this :)
BTW, I found similar code in:
1) net/ax25/af_ax25.c
2) net/rose/af_rose.c
I hope, this will help!
With regards,
Pavel Skripkin
next reply other threads:[~2021-05-05 17:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 17:02 Pavel Skripkin [this message]
2021-05-06 22:09 ` GPF in net sybsystem Jakub Kicinski
2021-05-07 0:40 ` Cong Wang
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