CVE-2026-72003: wifi: brcmfmac: cyw: fix heap overflow on a short auth frame

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

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

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

u32 mgmtframelen = e->datalen - sizeof(struct brcmfrxmgmtdata); ... memcpy(&mgmtframe->u, frame, mgmtframelen - offsetof(struct ieee80211mgmt, u));

The only length check is e->datalen >= sizeof(rxframe), so mgmtframelen can be anything from 0 up. offsetof(struct ieee80211mgmt, u) is 24. When mgmtframelen 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.