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nl80211: fix overflow in ssid_len

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When one of the SSID's length passed in a scan or sched_scan request
is larger than 255, there will be an overflow in the u8 that is used
to store the length before checking.  This causes the check to fail
and we overrun the buffer when copying the SSID.

Fix this by checking the nl80211 attribute length before copying it to
the struct.

This is a follow up for the previous commit
208c72f4fe, which didn't fix the problem
entirely.

Reported-by: Ido Yariv <ido@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Luciano Coelho 2011-06-07 20:42:26 +03:00 committed by John W. Linville
parent 6633d64978
commit 57a27e1d6a
1 changed files with 4 additions and 5 deletions
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9
net/wireless/nl80211.c
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@ -3406,11 +3406,11 @@ 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) {
if (nla_len(attr) > IEEE80211_MAX_SSID_LEN) {
err = -EINVAL;
goto out_free;
}
request->ssids[i].ssid_len = nla_len(attr);
memcpy(request->ssids[i].ssid, nla_data(attr), nla_len(attr));
i++;
}
@ -3572,12 +3572,11 @@ 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) {
if (nla_len(attr) > IEEE80211_MAX_SSID_LEN) {
err = -EINVAL;
goto out_free;
}
request->ssids[i].ssid_len = nla_len(attr);
memcpy(request->ssids[i].ssid, nla_data(attr),
nla_len(attr));
i++;