netfilter: ipt_CLUSTERIP: fix buffer overflow
'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@openwall.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 403ca57..d609ac3 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -664,8 +664,11 @@
char buffer[PROC_WRITELEN+1];
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);