linux-kernel - Re: [PATCH 3.2 08/67] af_unix: fix struct pid memory leak

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Date:	Tue, 23 Feb 2016 22:07:06 +0000
From:	Rainer Weikusat <rweikusat@...ileactivedefense.com>
To:	Ben Hutchings <ben@...adent.org.uk>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	akpm@...ux-foundation.org,
	"Rainer Weikusat" <rweikusat@...ileactivedefense.com>,
	"David S. Miller" <davem@...emloft.net>,
	"Eric Dumazet" <edumazet@...gle.com>,
	"Dmitry Vyukov" <dvyukov@...gle.com>
Subject: Re: [PATCH 3.2 08/67] af_unix: fix struct pid memory leak

Ben Hutchings <ben@...adent.org.uk> writes:
> 3.2.78-rc1 review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
> From: Eric Dumazet <edumazet@...gle.com>
>
> commit fa0dc04df259ba2df3ce1920e9690c7842f8fa4b upstream.

[...]

> Fixes: b3ca9b02b007 ("net: fix multithreaded signal handling in unix recv routines")

[...]

>  net/unix/af_unix.c | 1 +
>  1 file changed, 1 insertion(+)
>
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -2100,6 +2100,7 @@ static int unix_stream_recvmsg(struct ki
>  
>  			if (signal_pending(current)) {
>  				err = sock_intr_errno(timeo);
> +				scm_destroy(siocb->scm);
>  				goto out;
>  			}

JFTR: The commit mentioned in the fixes is (just the relevant part)

@@ -1895,11 +1903,12 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 
                        timeo = unix_stream_data_wait(sk, timeo);
 
-                       if (signal_pending(current)) {
+                       if (signal_pending(current)
+                           ||  mutex_lock_interruptible(&u->readlock)) {
                                err = sock_intr_errno(timeo);
                                goto out;
                        }
-                       mutex_lock(&u->readlock);
+
                        continue;
  unlock:
                        unix_state_unlock(sk);

This not only didn't add the block triggering the error but this change
isn't even part of the (version of) the function which was fixed
anymore.