From: Cyrill Gorcunov <gorcunov@gmail.com>
Date: Sun, 31 Aug 2008 15:25:49 +0000 (+0400)
Subject: sunrpc: fix possible overrun on read of /proc/sys/sunrpc/transports
X-Git-Tag: v2.6.27-rc6~83^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=27df6f25ff218072e0e879a96beeb398a79cdbc8;p=pandora-kernel.git

sunrpc: fix possible overrun on read of /proc/sys/sunrpc/transports

Vegard Nossum reported
----------------------
> I noticed that something weird is going on with /proc/sys/sunrpc/transports.
> This file is generated in net/sunrpc/sysctl.c, function proc_do_xprt(). When
> I "cat" this file, I get the expected output:
>    $ cat /proc/sys/sunrpc/transports
>    tcp 1048576
>    udp 32768

> But I think that it does not check the length of the buffer supplied by
> userspace to read(). With my original program, I found that the stack was
> being overwritten by the characters above, even when the length given to
> read() was just 1.

David Wagner added (among other things) that copy_to_user could be
probably used here.

Ingo Oeser suggested to use simple_read_from_buffer() here.

The conclusion is that proc_do_xprt doesn't check for userside buffer
size indeed so fix this by using Ingo's suggestion.

Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
CC: Ingo Oeser <ioe-lkml@rameria.de>
Cc: Neil Brown <neilb@suse.de>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Greg Banks <gnb@sgi.com>
Cc: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
---

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