Linux Kernel nl80211 Monitor Interface Flag Handling Vulnerability

A vulnerability in the Linux kernel's handling of monitor interface flags can lead to improper state management. When both MONITOR_FLAG_COOK_FRAMES and MONITOR_FLAG_ACTIVE are set simultaneously on the same monitor interface from userspace, it creates a sub-interface without the necessary IEEE80211_SDATA_IN_DRIVER bit. This issue arises because the cooked state takes precedence over other states, leading to a warning when the interface is deleted. The vulnerability has been addressed by rejecting MONITOR_FLAG_COOK_FRAMES when it is combined with other flags.

Impact

Exploitation of this vulnerability can cause a kernel warning due to improper management of monitor interface states, potentially leading to instability or unexpected behavior in the wireless subsystem.