CVE-2011-2517 (published 2012-05-24T23:55Z)

Multiple buffer overflows in net/wireless/nl80211.c in the Linux kernel before 2.6.39.2 allow local users to gain privileges by leveraging the CAP_NET_ADMIN capability during scan operations with a long SSID value.

Severity: HIGH
CVSS v2 base score: 7.2 (AV:L/AC:L/Au:N/C:C/I:C/A:C)

Weakness information:
cwe_id: CWE-119
cwe_name: Improper Restriction of Operations within the Bounds of a Memory Buffer
description: The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
extended_description: 
            Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data.
         
         

Fix information:
repo_url: https://github.com/torvalds/linux
commit_details: repo_url: https://github.com/torvalds/linux
author: Luciano Coelho
author_date: 2011-05-19 00:43:38+03:00
msg: nl80211: fix check for valid SSID size in scan operations

In both trigger_scan and sched_scan operations, we were checking for
the SSID length before assigning the value correctly.  Since the
memory was just kzalloc'ed, the check was always failing and SSID with
over 32 characters were allowed to go through.

This was causing a buffer overflow when copying the actual SSID to the
proper place.

This bug has been there since 2.6.29-rc4.

Cc: stable@kernel.org
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
repository: repo_url: https://github.com/torvalds/linux
repo_name: torvalds/linux
description: Linux kernel source tree
repo_language: C
owner: torvalds
file_changes: filename: nl80211.c
change_type: ModificationType.MODIFY
diff: @@ -3406,12 +3406,12 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
 	i = 0;
 	if (info->attrs[NL80211_ATTR_SCAN_SSIDS]) {
 		nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS], tmp) {
+			request->ssids[i].ssid_len = nla_len(attr);
 			if (request->ssids[i].ssid_len > IEEE80211_MAX_SSID_LEN) {
 				err = -EINVAL;
 				goto out_free;
 			}
 			memcpy(request->ssids[i].ssid, nla_data(attr), nla_len(attr));
-			request->ssids[i].ssid_len = nla_len(attr);
 			i++;
 		}
 	}
@@ -3572,6 +3572,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 	if (info->attrs[NL80211_ATTR_SCAN_SSIDS]) {
 		nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS],
 				    tmp) {
+			request->ssids[i].ssid_len = nla_len(attr);
 			if (request->ssids[i].ssid_len >
 			    IEEE80211_MAX_SSID_LEN) {
 				err = -EINVAL;
@@ -3579,7 +3580,6 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
 			}
 			memcpy(request->ssids[i].ssid, nla_data(attr),
 			       nla_len(attr));
-			request->ssids[i].ssid_len = nla_len(attr);
 			i++;
 		}
 	}

programming_language: C