netdev - Re: [Bugme-new] [Bug 14546] New: Off-by-two stack buffer overflow in function rpc

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Date:	Thu, 12 Nov 2009 16:56:47 +1100
From:	Neil Brown <neilb@...e.de>
To:	Chuck Lever <chuck.lever@...cle.com>
Cc:	Fabio Olive Leite <fabio.olive@...il.com>, argp@...sus-labs.com,
	bugzilla-daemon@...zilla.kernel.org,
	bugme-daemon@...zilla.kernel.org,
	Linux Network Developers <netdev@...r.kernel.org>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Trond Myklebust <trond.myklebust@....uio.no>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux NFS Mailing list <linux-nfs@...r.kernel.org>
Subject: Re: [Bugme-new] [Bug 14546] New: Off-by-two stack buffer overflow in function rpc_uaddr2sockaddr() of net/sunrpc/addr.c

On Wednesday November 11, chuck.lever@...cle.com wrote:
> On 2009-11-11 Fabio Olive Leite wrote:
> > On 2009-11-11 Patroklos Argyroudis wrote:
> >> There is no need to increase the size of the buffer since the new
> >> check (if (uaddr_len > sizeof(buf) - 2)) will terminate the function
> >> in case the valid universal address is RPCBIND_MAXUADDRLEN bytes.
> > On a second note, why is '\n' needed there? You should only need  
> > '\0', as a '\n'
> 
> > at the end is not required by any of the string functions used to  
> > convert the
> > address. I believe you could go with buf[RPCBIND_MAXUADDRLEN+1] for  
> > the extra NUL only.
> 
> AFAICT, strict_strtoul() requires the '\n\0' termination.

	if ((*tail == '\0') ||
		((len == (size_t)(tail - cp) + 1) && (*tail == '\n'))) {
		*res = val;
		return 0;
	}


allows, not requires.  Though admittedly that code isn't as clear as
one might like:
        if (tail[0] == 0 || (tail[0] == '\n' && tail[1] == 0) {
                .....
        }

NeilBrown
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