The ath9k_htc_set_bssid_mask function in drivers/net/wireless/ath/ath9k/htc_drv_main.c in the Linux kernel through 3.12 uses a BSSID masking approach to determine the set of MAC addresses on which a Wi-Fi device is listening, which allows remote attackers to discover the original MAC address after spoofing by sending a series of packets to MAC addresses with certain bit manipulations.
bugs.debian.org/cgi-bin/bugreport.cgi?bug=729573
www.mathyvanhoef.com/2013/11/unmasking-spoofed-mac-address.html
www.openwall.com/lists/oss-security/2013/11/15/3
www.ubuntu.com/usn/USN-2113-1
www.ubuntu.com/usn/USN-2117-1
www.ubuntu.com/usn/USN-2133-1
www.ubuntu.com/usn/USN-2134-1
www.ubuntu.com/usn/USN-2135-1
www.ubuntu.com/usn/USN-2136-1
www.ubuntu.com/usn/USN-2138-1
www.ubuntu.com/usn/USN-2139-1
www.ubuntu.com/usn/USN-2141-1
lists.ath9k.org/pipermail/ath9k-devel/2013-November/012215.html