BUG in sys_socketpair

BUG in sys_socketpair

[Rich Paul]

In 2.6.23, there seems to be a minor bug in sys_socketpair.  When the
calls to sock_alloc_fd fail, it aborts the routine, but it returns the
variable err, which is not set in this case.

The result is a silent failure if you have too many files open and call
socketpair.

Here is a simple UNTESTED patch (not even compiled) which should resolve the
issue.

Regards,
Rich

--- net/socket.c.orig   2007-10-25 10:03:56.000000000 -0400
+++ net/socket.c        2007-10-25 10:04:00.000000000 -0400
@@ -1245,11 +1245,14 @@
                goto out_release_both;

        fd1 = sock_alloc_fd(&newfile1);
-       if (unlikely(fd1 < 0))
+       if (unlikely(fd1 < 0)) {
+               err=fd1;
                goto out_release_both;
+       }

        fd2 = sock_alloc_fd(&newfile2);
        if (unlikely(fd2 < 0)) {
+               err=fd2;
                put_filp(newfile1);
                put_unused_fd(fd1);
                goto out_release_both;

Re: BUG in sys_socketpair

[Chuck Ebbert]

On 10/25/2007 10:11 AM, Rich Paul wrote:
> In 2.6.23, there seems to be a minor bug in sys_socketpair.  When the
> calls to sock_alloc_fd fail, it aborts the routine, but it returns the
> variable err, which is not set in this case.
> 
> The result is a silent failure if you have too many files open and call
> socketpair.
> 
> Here is a simple UNTESTED patch (not even compiled) which should resolve the
> issue.
> 
> 
> --- net/socket.c.orig   2007-10-25 10:03:56.000000000 -0400
> +++ net/socket.c        2007-10-25 10:04:00.000000000 -0400
> @@ -1245,11 +1245,14 @@
>                 goto out_release_both;
> 
>         fd1 = sock_alloc_fd(&newfile1);
> -       if (unlikely(fd1 < 0))
> +       if (unlikely(fd1 < 0)) {
> +               err=fd1;
>                 goto out_release_both;
> +       }
> 
>         fd2 = sock_alloc_fd(&newfile2);
>         if (unlikely(fd2 < 0)) {
> +               err=fd2;
>                 put_filp(newfile1);
>                 put_unused_fd(fd1);
>                 goto out_release_both;
> 

Should be "err = fd1" (spaces), otherwise looks good.

Original did:

	err = sock_map_fd(sock1);
	if (err < 0)
		goto out_release_both;
	fd1 = err;

Re: BUG in sys_socketpair

[David Miller]

From: Chuck Ebbert <cebbert@redhat.com>
Date: Thu, 25 Oct 2007 14:44:52 -0400

> On 10/25/2007 10:11 AM, Rich Paul wrote:
> > In 2.6.23, there seems to be a minor bug in sys_socketpair.  When the
> > calls to sock_alloc_fd fail, it aborts the routine, but it returns the
> > variable err, which is not set in this case.
> > 
> > The result is a silent failure if you have too many files open and call
> > socketpair.
> > 
> > Here is a simple UNTESTED patch (not even compiled) which should resolve the
> > issue.
> > 
> > 
> > --- net/socket.c.orig   2007-10-25 10:03:56.000000000 -0400
> > +++ net/socket.c        2007-10-25 10:04:00.000000000 -0400
> Should be "err = fd1" (spaces), otherwise looks good.
> 
> Original did:
> 
> 	err = sock_map_fd(sock1);
> 	if (err < 0)
> 		goto out_release_both;
> 	fd1 = err;

Thanks everyone, I'll commit the following both to 2.6.x GIT
and -stable.

>From 42f3fc7e989554e9952bdf28af137e4e4570f067 Mon Sep 17 00:00:00 2001
From: David S. Miller <davem@sunset.davemloft.net>
Date: Mon, 29 Oct 2007 21:54:02 -0700
Subject: [PATCH] [NET]: Fix error reporting in sys_socketpair().

If either of the two sock_alloc_fd() calls fail, we
forget to update 'err' and thus we'll erroneously
return zero in these cases.

Based upon a report and patch from Rich Paul, and
commentary from Chuck Ebbert.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/socket.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index 540013e..5d879fd 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1250,11 +1250,14 @@ asmlinkage long sys_socketpair(int family, int type, int protocol,
 		goto out_release_both;
 
 	fd1 = sock_alloc_fd(&newfile1);
-	if (unlikely(fd1 < 0))
+	if (unlikely(fd1 < 0)) {
+		err = fd1;
 		goto out_release_both;
+	}
 
 	fd2 = sock_alloc_fd(&newfile2);
 	if (unlikely(fd2 < 0)) {
+		err = fd2;
 		put_filp(newfile1);
 		put_unused_fd(fd1);
 		goto out_release_both;
-- 
1.5.2.5