Re: [Bugme-new] [Bug 14546] New: Off-by-two stack buffer overflow in function rpc_uaddr2sockaddr() of net/sunrpc/addr.c

[Andrew Morton <akpm@linux-foundation.org>]

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Thu, 5 Nov 2009 10:31:03 GMT
bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r@public.gmane.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=14546
> 
>            Summary: Off-by-two stack buffer overflow in function
>                     rpc_uaddr2sockaddr() of net/sunrpc/addr.c
>            Product: Networking
>            Version: 2.5
>     Kernel Version: 2.6.32-rc6
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: Other
>         AssignedTo: acme-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org
>         ReportedBy: argp-YZAGAMbGdGKGw+nKnLezzg@public.gmane.org
>                 CC: argp-YZAGAMbGdGKGw+nKnLezzg@public.gmane.org
>         Regression: No
> 
> 
> There is an off-by-two stack buffer overflow in function rpc_uaddr2sockaddr()
> of file net/sunrpc/addr.c in the Linux kernel SUNRPC implementation.
> 
> The function rpc_uaddr2sockaddr() that is used to convert a universal address
> to a socket address takes as an argument the size_t variable uaddr_len (the
> length of the universal address string). The stack buffer buf is declared in
> line 315 to be of size RPCBIND_MAXUADDRLEN. If the passed argument uaddr_len is
> equal to RPCBIND_MAXUADDRLEN then the check at line 319 passes and then at
> lines 324 and 325 there are two out-of-bounds assignments:
> 
>     319         if (uaddr_len > sizeof(buf))
>     320                 return 0;
> ...
>     324         buf[uaddr_len] = '\n';
>     325         buf[uaddr_len + 1] = '\0';
> 
> To fix it please see the attached patch.
> 

Please don't submit patches via bugzilla. 

Please prepare this patch as per Documentation/SubmittingPatches and
email it to all the recipients of this email, thanks.

--- ./net/sunrpc/addr.c.orig	2009-11-05 11:55:45.000000000 +0200
+++ ./net/sunrpc/addr.c	2009-11-05 12:09:34.000000000 +0200
@@ -316,7 +316,7 @@
 	unsigned long portlo, porthi;
 	unsigned short port;
 
-	if (uaddr_len > sizeof(buf))
+	if (uaddr_len > sizeof(buf) - 2)
 		return 0;
 
 	memcpy(buf, uaddr, uaddr_len);