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

commit 68abd0c4ebf24cd499841a488b97a6873d5efabb upstream.

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.

Cc: stable@vger.kernel.org
Signed-off-by: Marcel Hamer <marcel.hamer@windriver.com>
Link: https://lore.kernel.org/all/b519e746-ddfd-421f-d897-7620d229e4b2@gmail.com/
Acked-by: Arend van Spriel  <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20250116132240.731039-1-marcel.hamer@windriver.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
index 3d544eedc1a395ef41f0643e9ae94b968a8c0d8c..35dd99dd7dfd14e46d58503e97e361b7ddf115f6 100644 (file)
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
@@ -545,6 +545,11 @@ void brcmf_txfinalize(struct brcmf_if *ifp, struct sk_buff *txp, bool success)
        struct ethhdr *eh;
        u16 type;
 
+       if (!ifp) {
+               brcmu_pkt_buf_free_skb(txp);
+               return;
+       }
+
        eh = (struct ethhdr *)(txp->data);
        type = ntohs(eh->h_proto);