CVE-2025-40321
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-08

Last updated on: 2025-12-08

Assigner: kernel.org

Description
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]
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Meta Information
Published
2025-12-08
Last Modified
2025-12-08
Generated
2026-05-07
AI Q&A
2025-12-08
EPSS Evaluated
2026-05-05
NVD
CVE-2025-40321
EUVD
EUVD-2025-201624
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
brcm brcmfmac *
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel's brcmfmac driver when sending Action frames in standalone AP mode managed only by hostapd. The driver incorrectly uses a P2P vif pointer that is not initialized in this mode, leading to a NULL pointer dereference and a kernel crash. The issue arises because the P2P interfaces are only created when wpa_supplicant manages the wlan interface, not when hostapd does. The fix involves using the vif corresponding to the wireless device initiating the Action frame transmission, ensuring the driver does not crash even if the P2P vif is unavailable.


How can this vulnerability impact me? :

This vulnerability can cause the Linux kernel to crash due to a NULL pointer dereference in the brcmfmac driver when handling certain Action frames in standalone AP mode. This crash can lead to denial of service on affected devices, such as Raspberry Pi 4 Model B, disrupting network connectivity and device availability.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring kernel logs for crashes related to the brcmfmac driver, specifically NULL pointer dereferences when sending Action frames in standalone AP mode. You can check the kernel log for messages similar to: 'Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000' and call traces involving brcmf_p2p_send_action_frame and brcmfmac. Commands to check logs include: 'dmesg | grep brcmfmac' or 'journalctl -k | grep brcmfmac'.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves updating the Linux kernel to a version where the brcmfmac driver has been fixed to handle Action frame transmissions correctly in standalone AP mode. This fix ensures the driver uses the correct vif pointer and prevents NULL pointer dereferences. Until an update is applied, avoid configurations where hostapd manages the wlan interface alone with brcmfmac, or monitor and restart the affected service if crashes occur.


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