CVE-2025-21744

/// Technical description

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

wifi: brcmfmac: fix NULL pointer dereference in brcmf_txfinalize()

On removal of the device or unloading of the kernel module a potential NULL

pointer dereference occurs.

The following sequence deletes the interface:

brcmf_detach()

brcmf_remove_interface()

brcmf_del_if()

Inside the brcmf_del_if() function the drvr->if2bss[ifidx] is updated to

BRCMF_BSSIDX_INVALID (-1) if the bsscfgidx matches.

After brcmf_remove_interface() call the brcmf_proto_detach() function is

called providing the following sequence:

brcmf_detach()

brcmf_proto_detach()

brcmf_proto_msgbuf_detach()

brcmf_flowring_detach()

brcmf_msgbuf_delete_flowring()

brcmf_msgbuf_remove_flowring()

brcmf_flowring_delete()

brcmf_get_ifp()

brcmf_txfinalize()

Since brcmf_get_ip() can and actually will return NULL in this case the

call to brcmf_txfinalize() will

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References