cve/published/2025/CVE-2025-21744.mbox

From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: <linux-cve-announce@vger.kernel.org>
Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
Subject: CVE-2025-21744: wifi: brcmfmac: fix NULL pointer dereference in brcmf_txfinalize()

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 result in a NULL pointer dereference inside
brcmf_txfinalize() when trying to update ifp->ndev->stats.tx_errors.

This will only happen if a flowring still has an skb.

Although the NULL pointer dereference has only been seen when trying to
update the tx statistic, all other uses of the ifp pointer have been
guarded as well with an early return if ifp is NULL.

The Linux kernel CVE team has assigned CVE-2025-21744 to this issue.


Affected and fixed versions
===========================

	Fixed in 5.4.291 with commit 2326e19190e176fd72bb542b837a9d2b7fcb8693
	Fixed in 5.10.235 with commit 59ff4fa653ff6db07c61152516ffba79c2a74bda
	Fixed in 5.15.179 with commit 61541d9b5a23df33934fcc620a3a81f246b1b240
	Fixed in 6.1.129 with commit 4e51d6d093e763348916e69d06d87e0a5593661b
	Fixed in 6.6.78 with commit 3877fc67bd3d5566cc12763bce39710ceb74a97d
	Fixed in 6.12.14 with commit fbbfef2a5b858eab55741a58b2ac9a0cc8d53c58
	Fixed in 6.13.3 with commit a2beefc4fa49ebc22e664dc6b39dbd054f8488f9
	Fixed in 6.14 with commit 68abd0c4ebf24cd499841a488b97a6873d5efabb

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-21744
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/2326e19190e176fd72bb542b837a9d2b7fcb8693
	https://git.kernel.org/stable/c/59ff4fa653ff6db07c61152516ffba79c2a74bda
	https://git.kernel.org/stable/c/61541d9b5a23df33934fcc620a3a81f246b1b240
	https://git.kernel.org/stable/c/4e51d6d093e763348916e69d06d87e0a5593661b
	https://git.kernel.org/stable/c/3877fc67bd3d5566cc12763bce39710ceb74a97d
	https://git.kernel.org/stable/c/fbbfef2a5b858eab55741a58b2ac9a0cc8d53c58
	https://git.kernel.org/stable/c/a2beefc4fa49ebc22e664dc6b39dbd054f8488f9
	https://git.kernel.org/stable/c/68abd0c4ebf24cd499841a488b97a6873d5efabb