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

Overview

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 event while the interface is in AP/uAP mode.

Validate event->len before use: reject a length that underflows the header or that would place the IEs outside the event_body[] buffer the event was copied into. event->len here is struct mwifiex_assoc_event.len, a payload field internal to this event, not the transport frame length, so it is validated in this handler rather than at the generic MWIFIEX_TYPE_EVENT receive path, which only sees the event cause and the transport frame length. The bound is against event_body[MAX_EVENT_SIZE] rather than the actually-received length because the transports store the event differently (USB and SDIO leave the 4-byte event header in event_skb, PCIe strips it via skb_pull), whereas event_body is the single fixed buffer all of them copy the event into. This is the event-path analogue of the receive-path bounds checks added in commit 119585281617 ("wifi: mwifiex: Fix OOB and integer underflow when rx packets").

Affected

• Linux >= e568634ae7ac379661c90731d480e067929420a1 < a616616b938f7922a93e79bef16b4643c57c0922
• Linux >= e568634ae7ac379661c90731d480e067929420a1 < 1ae00b6d9a6c82eb3de151d9b04ed59e06cc100f
• Linux >= e568634ae7ac379661c90731d480e067929420a1 < e7e93d3e8c240bdb70c41e79d169d74dfb442843
• Linux >= e568634ae7ac379661c90731d480e067929420a1 < a3f47d7c75ddad1a14621a309286f9fae3cba191
• Linux >= e568634ae7ac379661c90731d480e067929420a1 < ad26c75ae25749313248f06510ebe43b5bf4adcc
• Linux >= e568634ae7ac379661c90731d480e067929420a1 < d21464d93f8ba464dc3d7b4b31c6e0adcd9f659c
• Linux >= e568634ae7ac379661c90731d480e067929420a1 < b6766d7ea43edf5de9d5a572bc58b631d09efe4b
• Linux >= e568634ae7ac379661c90731d480e067929420a1 < f0858bfc7d3cab411a447b88e3ef970e575032c9
• Linux 3.5

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.