[PATCH net] net/smc: fix refcount non-blocking connect() -part 2

[PATCH net] net/smc: fix refcount non-blocking connect() -part 2

[Karsten Graul]

From: Ursula Braun <ubraun@linux.ibm.com>

If an SMC socket is immediately terminated after a non-blocking connect()
has been called, a memory leak is possible.
Due to the sock_hold move in
commit 301428ea3708 ("net/smc: fix refcounting for non-blocking connect()")
an extra sock_put() is needed in smc_connect_work(), if the internal
TCP socket is aborted and cancels the sk_stream_wait_connect() of the
connect worker.

Reported-by: syzbot+4b73ad6fc767e576e275@syzkaller.appspotmail.com
Fixes: 301428ea3708 ("net/smc: fix refcounting for non-blocking connect()")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
---
 net/smc/af_smc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index cde4dc0ed173..d0271bcb2191 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -799,6 +799,7 @@ static void smc_connect_work(struct work_struct *work)
 			smc->sk.sk_err = EPIPE;
 		else if (signal_pending(current))
 			smc->sk.sk_err = -sock_intr_errno(timeo);
+		sock_put(&smc->sk); /* passive closing */
 		goto out;
 	}
 
-- 
2.17.1

Re: [PATCH net] net/smc: fix refcount non-blocking connect() -part 2

[David Miller]

From: Karsten Graul <kgraul@linux.ibm.com>
Date: Tue, 12 Nov 2019 16:03:41 +0100

> From: Ursula Braun <ubraun@linux.ibm.com>
> 
> If an SMC socket is immediately terminated after a non-blocking connect()
> has been called, a memory leak is possible.
> Due to the sock_hold move in
> commit 301428ea3708 ("net/smc: fix refcounting for non-blocking connect()")
> an extra sock_put() is needed in smc_connect_work(), if the internal
> TCP socket is aborted and cancels the sk_stream_wait_connect() of the
> connect worker.
> 
> Reported-by: syzbot+4b73ad6fc767e576e275@syzkaller.appspotmail.com
> Fixes: 301428ea3708 ("net/smc: fix refcounting for non-blocking connect()")
> Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
> Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>

Applied.

And since 301428ea3708 went to -stable, I'll queue this up too.

Thanks.