[43/71] netfilter: ipt_CLUSTERIP: fix buffer overflow

From: Greg KH
Date: Wed Apr 13 2011 - 12:21:40 EST

2.6.33-longterm review patch. If anyone has any objections, please let us know.


From: Vasiliy Kulikov <segoon@xxxxxxxxxxxx>

commit 961ed183a9fd080cf306c659b8736007e44065a5 upstream.

'buffer' string is copied from userspace. It is not checked whether it is
zero terminated. This may lead to overflow inside of simple_strtoul().
Changli Gao suggested to copy not more than user supplied 'size' bytes.

It was introduced before the git epoch. Files "ipt_CLUSTERIP/*" are
root writable only by default, however, on some setups permissions might be
relaxed to e.g. network admin user.

Signed-off-by: Vasiliy Kulikov <segoon@xxxxxxxxxxxx>
Acked-by: Changli Gao <xiaosuo@xxxxxxxxx>
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

net/ipv4/netfilter/ipt_CLUSTERIP.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -666,8 +666,11 @@ static ssize_t clusterip_proc_write(stru
struct clusterip_config *c = pde->data;
unsigned long nodenum;

- if (copy_from_user(buffer, input, PROC_WRITELEN))
+ if (size > PROC_WRITELEN)
+ return -EIO;
+ if (copy_from_user(buffer, input, size))
return -EFAULT;
+ buffer[size] = 0;

if (*buffer == '+') {
nodenum = simple_strtoul(buffer+1, NULL, 10);

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