lkml.org 
[lkml]   [2008]   [Sep]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch 03/16] sunrpc: fix possible overrun on read of /proc/sys/sunrpc/transports

2.6.25-stable review patch. If anyone has any objections, please let us know.

------------------
From: Cyrill Gorcunov <gorcunov@gmail.com>

commit 27df6f25ff218072e0e879a96beeb398a79cdbc8 upstream

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/sunrpc/sysctl.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)

--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -60,24 +60,14 @@ static int proc_do_xprt(ctl_table *table
void __user *buffer, size_t *lenp, loff_t *ppos)
{
char tmpbuf[256];
- int len;
+ size_t len;
+
if ((*ppos && !write) || !*lenp) {
*lenp = 0;
return 0;
}
- if (write)
- return -EINVAL;
- else {
- len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
- if (!access_ok(VERIFY_WRITE, buffer, len))
- return -EFAULT;
-
- if (__copy_to_user(buffer, tmpbuf, len))
- return -EFAULT;
- }
- *lenp -= len;
- *ppos += len;
- return 0;
+ len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
+ return simple_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
}

static int
--


\
 
 \ /
  Last update: 2008-09-03 19:53    [W:0.069 / U:0.444 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site