Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

wifi: mwifiex: bound uAP association event IEs to the event buffer

mwifiex_process_uap_event() handles EVENT_UAP_STA_ASSOC by exposing the (re)association request IEs that the firmware copies into the event:

sinfo->assoc_req_ies = &event->data[len]; len = (u8 *)sinfo->assoc_req_ies - (u8 *)&event->frame_control; sinfo->assoc_req_ies_len = le16_to_cpu(event->len) - (u16)len;

event->len is supplied by the device firmware and is never validated, and the subtraction is unchecked. assoc_req_ies points into adapter->event_body[MAX_EVENT_SIZE], a fixed-size array embedded in the kmalloc()'d struct mwifiex_adapter.

On the ap_11n_enabled path mwifiex_set_sta_ht_cap() walks these IEs with cfg80211_find_ie(), whose for_each_element() loop dereferences each element header. A firmware-reported event->len larger than the bytes actually received makes assoc_req_ies_len describe IEs that extend past event_body, so the walk reads out of the adapter slab object, a slab-out-of-bounds read (KASAN: slab-out-of-bounds in cfg80211_find_ie). An event->len smaller than the header instead makes the int subtraction negative, which wraps to a huge size_t when stored in assoc_req_ies_len. The same length is handed to cfg80211_new_sta(), so a more modest over-claim can also copy stale event_body bytes into the NL80211_CMD_NEW_STATION notification.

A malicious or malfunctioning mwifiex device (USB/SDIO/PCIe) can deliver such an…