nl80211: fix check for valid SSID size in scan operations

Luciano Coelho · linvjw · commit 208c72f4fe44 · 2011-05-26T15:43:28.000-04:00
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 &lt;coelho@ti.com&gt;
Signed-off-by: John W. Linville &lt;linville@tuxdriver.com&gt;
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
@@ -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++;
 		}
 	}
@@ -3572,14 +3572,14 @@ 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;
 				goto out_free;
 			}
 			memcpy(request->ssids[i].ssid, nla_data(attr),
 			       nla_len(attr));
-			request->ssids[i].ssid_len = nla_len(attr);
 			i++;
 		}
 	}

Original file line number	Diff line number	Diff line change
`@@ -3406,12 +3406,12 @@ static int nl80211_trigger_scan(struct sk_buff skb, struct genl_info info)`
`3406`	`3406`	`i = 0;`
`3407`	`3407`	`if (info->attrs[NL80211_ATTR_SCAN_SSIDS]) {`
`3408`	`3408`	`nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS], tmp) {`
	`3409`	`+ request->ssids[i].ssid_len = nla_len(attr);`
`3409`	`3410`	`if (request->ssids[i].ssid_len > IEEE80211_MAX_SSID_LEN) {`
`3410`	`3411`	`err = -EINVAL;`
`3411`	`3412`	`goto out_free;`
`3412`	`3413`	`}`
`3413`	`3414`	`memcpy(request->ssids[i].ssid, nla_data(attr), nla_len(attr));`
`3414`		`- request->ssids[i].ssid_len = nla_len(attr);`
`3415`	`3415`	`i++;`
`3416`	`3416`	`}`
`3417`	`3417`	`}`
`@@ -3572,14 +3572,14 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,`
`3572`	`3572`	`if (info->attrs[NL80211_ATTR_SCAN_SSIDS]) {`
`3573`	`3573`	`nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS],`
`3574`	`3574`	`tmp) {`
	`3575`	`+ request->ssids[i].ssid_len = nla_len(attr);`
`3575`	`3576`	`if (request->ssids[i].ssid_len >`
`3576`	`3577`	`IEEE80211_MAX_SSID_LEN) {`
`3577`	`3578`	`err = -EINVAL;`
`3578`	`3579`	`goto out_free;`
`3579`	`3580`	`}`
`3580`	`3581`	`memcpy(request->ssids[i].ssid, nla_data(attr),`
`3581`	`3582`	`nla_len(attr));`
`3582`		`- request->ssids[i].ssid_len = nla_len(attr);`
`3583`	`3583`	`i++;`
`3584`	`3584`	`}`
`3585`	`3585`	`}`