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.

https://git.kernel.org/stable/c/3877fc67bd3d5566cc12763bce39710ceb74a97d

https://git.kernel.org/stable/c/4e51d6d093e763348916e69d06d87e0a5593661b

https://git.kernel.org/stable/c/68abd0c4ebf24cd499841a488b97a6873d5efabb

https://git.kernel.org/stable/c/a2beefc4fa49ebc22e664dc6b39dbd054f8488f9

https://git.kernel.org/stable/c/fbbfef2a5b858eab55741a58b2ac9a0cc8d53c58