CVE-2025-40321: 
Linux Kernel vulnerability analysis and mitigation

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

wifi: brcmfmac: fix crash while sending Action Frames in standalone AP Mode

Currently, whenever there is a need to transmit an Action frame, the brcmfmac driver always uses the P2P vif to send the "actframe" IOVAR to firmware. The P2P interfaces were available when wpa_supplicant is managing the wlan interface.

However, the P2P interfaces are not created/initialized when only hostapd is managing the wlan interface. And if hostapd receives an ANQP Query REQ Action frame even from an un-associated STA, the brcmfmac driver tries to use an uninitialized P2P vif pointer for sending the IOVAR to firmware. This NULL pointer dereferencing triggers a driver crash.

[ 1417.074538] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [...] [ 1417.075188] Hardware name: Raspberry Pi 4 Model B Rev 1.5 (DT) [...] [ 1417.075653] Call trace: [ 1417.075662] brcmf_p2p_send_action_frame+0x23c/0xc58 [brcmfmac] [ 1417.075738] brcmf_cfg80211_mgmt_tx+0x304/0x5c0 [brcmfmac] [ 1417.075810] cfg80211_mlme_mgmt_tx+0x1b0/0x428 [cfg80211] [ 1417.076067] nl80211_tx_mgmt+0x238/0x388 [cfg80211] [ 1417.076281] genl_family_rcv_msg_doit+0xe0/0x158 [ 1417.076302] genl_rcv_msg+0x220/0x2a0 [ 1417.076317] netlink_rcv_skb+0x68/0x140 [ 1417.076330] genl_rcv+0x40/0x60 [ 1417.076343] netlink_unicast+0x330/0x3b8 [ 1417.076357] netlink_sendmsg+0x19c/0x3f8 [ 1417.076370] __sock_sendmsg+0x64/0xc0 [ 1417.076391] ____sys_sendmsg+0x268/0x2a0 [ 1417.076408] ___sys_sendmsg+0xb8/0x118 [ 1417.076427] __sys_sendmsg+0x90/0xf8 [ 1417.076445] __arm64_sys_sendmsg+0x2c/0x40 [ 1417.076465] invoke_syscall+0x50/0x120 [ 1417.076486] el0_svc_common.constprop.0+0x48/0xf0 [ 1417.076506] do_el0_svc+0x24/0x38 [ 1417.076525] el0_svc+0x30/0x100 [ 1417.076548] el0t_64_sync_handler+0x100/0x130 [ 1417.076569] el0t_64_sync+0x190/0x198 [ 1417.076589] Code: f9401e80 aa1603e2 f9403be1 5280e483 (f9400000)

Fix this, by always using the vif corresponding to the wdev on which the Action frame Transmission request was initiated by the userspace. This way, even if P2P vif is not available, the IOVAR is sent to firmware on AP vif and the ANQP Query RESP Action frame is transmitted without crashing the driver.

Move init_completion() for "send_af_done" from brcmf_p2p_create_p2pdev() to brcmf_p2p_attach(). Because the former function would not get executed when only hostapd is managing wlan interface, and it is not safe to do reinit_completion() later in brcmf_p2p_tx_action_frame(), without any prior init_completion().

And in the brcmf_p2p_tx_action_frame() function, the condition check for P2P Presence response frame is not needed, since the wpa_supplicant is properly sending the P2P Presense Response frame on the P2P-GO vif instead of the P2P-Device vif.

[Cc stable]