| From bfields@citi.umich.edu Wed Sep 3 09:39:03 2008 |
| From: Cyrill Gorcunov <gorcunov@gmail.com> |
| Date: Mon, 1 Sep 2008 14:51:01 -0400 |
| Subject: sunrpc: fix possible overrun on read of /proc/sys/sunrpc/transports |
| To: stable@kernel.org |
| Cc: linux-nfs@vger.kernel.org, Greg Banks <gnb@sgi.com>, Neil Brown <neilb@suse.de>, "J. Bruce Fields" <bfields@citi.umich.edu>, linux-kernel@vger.kernel.org, Tom Tucker <tom@opengridcomputing.com>, Ingo Oeser <ioe-lkml@rameria.de>, Cyrill Gorcunov <gorcunov@gmail.com>, Chuck Lever <chuck.lever@oracle.com> |
| Message-ID: <1220295062-10957-1-git-send-email-bfields@citi.umich.edu> |
| |
| |
| 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 |