Vulnerability: Multiple stack-based buffer overflows in net/netfilter/ipvs/ip_vs_ctl.c in the Linux kernel before 2.6.33, when CONFIG_IP_VS is used, allow local users to gain privileges by leveraging the CAP_NET_ADMIN capability for (1) a getsockopt system call, related to the do_ip_vs_get_ctl function, or (2) a setsockopt system call, related to the do_ip_vs_set_ctl function.
Vulnerability ID: CVE-2013-4588
CWE: CWE-119
Severity score: 10
Project: https://github.com/torvalds/linux
Published: 2013-11-20
File: net/netfilter/ipvs/ip_vs_ctl.c
Commit message: ipvs: Add boundary check on ioctl arguments

The ipvs code has a nifty system for doing the size of ioctl command
copies; it defines an array with values into which it indexes the cmd
to find the right length.

Unfortunately, the ipvs code forgot to check if the cmd was in the
range that the array provides, allowing for an index outside of the
array, which then gives a "garbage" result into the length, which
then gets used for copying into a stack buffer.

Fix this by adding sanity checks on these as well as the copy size.

[ horms@verge.net.au: adjusted limit to IP_VS_SO_GET_MAX ]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Commit author: Arjan van de Ven

Vulnerable version (before fix):
 do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len) 	if (!capable(CAP_NET_ADMIN)) 		return -EPERM;  	if (len != set_arglen[SET_CMDID(cmd)]) { 		pr_err("set_ctl: len %u != %u\n", 		       len, set_arglen[SET_CMDID(cmd)]); do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len) { 	unsigned char arg[128]; 	int ret = 0;  	if (!capable(CAP_NET_ADMIN)) 		return -EPERM;  	if (*len < get_arglen[GET_CMDID(cmd)]) { 		pr_err("get_ctl: len %u < %u\n", 		       *len, get_arglen[GET_CMDID(cmd)]); 		return -EINVAL; 	}  	if (copy_from_user(arg, user, get_arglen[GET_CMDID(cmd)]) != 0) 		return -EFAULT;  	if (mutex_lock_interruptible(&__ip_vs_mutex))

Fixed version (after fix):
 do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len) 	if (!capable(CAP_NET_ADMIN)) 		return -EPERM;  	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX) 		return -EINVAL; 	if (len < 0 || len >  MAX_ARG_LEN) 		return -EINVAL; 	if (len != set_arglen[SET_CMDID(cmd)]) { 		pr_err("set_ctl: len %u != %u\n", 		       len, set_arglen[SET_CMDID(cmd)]); do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len) { 	unsigned char arg[128]; 	int ret = 0; 	unsigned int copylen;  	if (!capable(CAP_NET_ADMIN)) 		return -EPERM;  	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_GET_MAX) 		return -EINVAL;  	if (*len < get_arglen[GET_CMDID(cmd)]) { 		pr_err("get_ctl: len %u < %u\n", 		       *len, get_arglen[GET_CMDID(cmd)]); 		return -EINVAL; 	}  	copylen = get_arglen[GET_CMDID(cmd)]; 	if (copylen > 128) 		return -EINVAL;  	if (copy_from_user(arg, user, copylen) != 0) 		return -EFAULT;  	if (mutex_lock_interruptible(&__ip_vs_mutex))

Patch:
patch: @@ -2077,6 +2077,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
 
+	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX)
+		return -EINVAL;
+	if (len < 0 || len >  MAX_ARG_LEN)
+		return -EINVAL;
 	if (len != set_arglen[SET_CMDID(cmd)]) {
 		pr_err("set_ctl: len %u != %u\n",
 		       len, set_arglen[SET_CMDID(cmd)]);
@@ -2352,17 +2356,25 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 {
 	unsigned char arg[128];
 	int ret = 0;
+	unsigned int copylen;
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
 
+	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_GET_MAX)
+		return -EINVAL;
+
 	if (*len < get_arglen[GET_CMDID(cmd)]) {
 		pr_err("get_ctl: len %u < %u\n",
 		       *len, get_arglen[GET_CMDID(cmd)]);
 		return -EINVAL;
 	}
 
-	if (copy_from_user(arg, user, get_arglen[GET_CMDID(cmd)]) != 0)
+	copylen = get_arglen[GET_CMDID(cmd)];
+	if (copylen > 128)
+		return -EINVAL;
+
+	if (copy_from_user(arg, user, copylen) != 0)
 		return -EFAULT;
 
 	if (mutex_lock_interruptible(&__ip_vs_mutex))
path: net/netfilter/ipvs/ip_vs_ctl.c