wifi: brcmfmac: cyw: fix heap overflow on a short auth frame

Overview

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

wifi: brcmfmac: cyw: fix heap overflow on a short auth frame

brcmf_notify_auth_frame_rx() takes the frame length from the firmware event and copies the frame body with the management header offset subtracted:

u32 mgmt_frame_len = e->datalen - sizeof(struct brcmf_rx_mgmt_data);
...
memcpy(&mgmt_frame->u, frame,
       mgmt_frame_len - offsetof(struct ieee80211_mgmt, u));

The only length check is e->datalen >= sizeof(*rxframe), so mgmt_frame_len can be anything from 0 up. offsetof(struct ieee80211_mgmt, u) is 24. When mgmt_frame_len is below that, the subtraction wraps as an unsigned value to a huge length. The memcpy then runs far past the kzalloc'd buffer. A malicious or malfunctioning AP can make the frame short during the external SAE auth exchange, so this is a remotely triggered heap overflow.

Reject frames shorter than the management header offset before the copy.

Affected

• Linux >= 66f909308a7c05082919ff214a0bbe2a76aa0283 < 55b26abb1fa1ec406b3ad11b43c49c7624257565
• Linux >= 66f909308a7c05082919ff214a0bbe2a76aa0283 < 185bb156c427d0f865d344a6d0eaa02c6d05cc57
• Linux >= 66f909308a7c05082919ff214a0bbe2a76aa0283 < 240c8d2c717b3f8153e7e877b22a82518d78dbdc
• Linux 6.16

Remediation

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