In the Linux kernel, the following vulnerability has been resolved:
wifi: cfg80211: bound element ID read when checking non-inheritance
cfg80211_is_element_inherited() reads the first data octet of the
candidate element (id = elem->data[0]) to look it up in an extension
non-inheritance list. It does so after testing elem->id, but without
verifying that the element actually has a data octet. A zero-length
extension element (WLAN_EID_EXTENSION with length 0) therefore makes it
read one octet past the end of the element.
_ieee802_11_parse_elems_full() runs this check for every element of a
frame once a non-inheritance context exists — e.g. while parsing a
per-STA profile of a Multi-Link element in a (re)association response,
or a non-transmitted BSS profile — so a crafted frame from an AP can
trigger a one-octet slab-out-of-bounds read during element parsing:
BUG: KASAN: slab-out-of-bounds in cfg80211_is_element_inherited
Read of size 1 … in net/wireless/scan.c
Return early (treat the element as inherited) when an extension element
carries no data, mirroring the existing handling of empty ID lists.
The bug was found by fuzzing ieee802_11_parse_elems_full() under KASAN.
