Date: Sat, 9 May 2015 21:20:36 +0300 From: Jouni Malinen <j@...fi> To: oss-security@...ts.openwall.com Subject: CVE request: hostapd/wpa_supplicant - Integer underflow in AP mode WMM Action frame processing Could a CVE please be assigned for following? Integer underflow in AP mode WMM Action frame processing Published: May 4, 2015 Latest version available from: http://w1.fi/security/2015-3/ Vulnerability A vulnerability was found in WMM Action frame processing in a case where hostapd or wpa_supplicant is used to implement AP mode MLME/SME functionality (i.e., Host AP driver of a mac80211-based driver on Linux). The AP mode WMM Action frame parser in hostapd/wpa_supplicant goes through the variable length information element part with the length of this area calculated by removing the header length from the total length of the frame. The frame length is previously verified to be large enough to include the IEEE 802.11 header, but the couple of additional bytes after this header are not explicitly verified and as a result of this, there may be an integer underflow that results in the signed integer variable storing the length becoming negative. This negative value is then interpreted as a very large unsigned integer length when parsing the information elements. This results in a buffer read overflow and process termination. This vulnerability can be used to perform denial of service attacks by an attacker that is within radio range of the AP that uses hostapd of wpa_supplicant for MLME/SME operations. Vulnerable versions/configurations hostapd v0.5.5-v2.4 with CONFIG_DRIVER_HOSTAP=y or CONFIG_DRIVER_NL80211=y in the build configuration (hostapd/.config). wpa_supplicant v0.7.0-v2.4 with CONFIG_AP=y or CONFIG_P2P=y and CONFIG_DRIVER_HOSTAP=y or CONFIG_DRIVER_NL80211=y in the build configuration (wpa_supplicant/.config) and AP (including P2P GO) mode used at runtime. Acknowledgments Thanks to Kostya Kortchinsky of Google Security Team for discovering and reporting this issue. Possible mitigation steps - Merge the following commit and rebuild hostapd/wpa_supplicant: AP WMM: Fix integer underflow in WMM Action frame parser This patch is available from http://w1.fi/security/2015-3/ - Update to hostapd/wpa_supplicant v2.5 or newer, once available - wpa_supplicant: Do not enable AP mode or P2P GO operation at runtime -- Jouni Malinen PGP id EFC895FA
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