linux-kernel - Re: [PATCH 1/1] NET: netpoll, fix potential NULL ptr dereference

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1268759527.25503.2980.camel@calx>
Date:	Tue, 16 Mar 2010 12:12:07 -0500
From:	Matt Mackall <mpm@...enic.com>
To:	Jiri Slaby <jslaby@...e.cz>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, jirislaby@...il.com,
	Daniel Borkmann <danborkmann@...glemail.com>
Subject: Re: [PATCH 1/1] NET: netpoll, fix potential NULL ptr dereference

On Tue, 2010-03-16 at 16:29 +0100, Jiri Slaby wrote:
> Stanse found that one error path in netpoll_setup dereferences npinfo
> even though it is NULL. Avoid that by adding new label and go to that
> instead.
> 
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> Cc: Daniel Borkmann <danborkmann@...glemail.com>
> Cc: David S. Miller <davem@...emloft.net>
> ---
>  net/core/netpoll.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/netpoll.c b/net/core/netpoll.c
> index 7aa6972..d4ec38f 100644
> --- a/net/core/netpoll.c
> +++ b/net/core/netpoll.c
> @@ -735,7 +735,7 @@ int netpoll_setup(struct netpoll *np)
>  		npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
>  		if (!npinfo) {
>  			err = -ENOMEM;
> -			goto release;
> +			goto put;
>  		}
>  
>  		npinfo->rx_flags = 0;
> @@ -845,7 +845,7 @@ int netpoll_setup(struct netpoll *np)
>  
>  		kfree(npinfo);
>  	}
> -
> +put:
>  	dev_put(ndev);
>  	return err;
>  }

I don't get it. The source of the branch tests for !ndev->npinfo and the
original destination of the branch also tests for !ndev->npinfo. I don't
see how it gets dereferenced.

This looks like it just patches over a false positive in your tool
(which isn't correlating the validity of npinfo with ndev->npinfo)
without actually improving the code. However, it seems that we can drop
the second check at release if we add your new exit point.

-- 
http://selenic.com : development and support for Mercurial and Linux


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/