On 1/10/2025 2:45 PM, Marcel Hamer wrote:
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.
Here my suggestion to make it a bit more simple...
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/
v1 -> v2: guard all uses of the ifp pointer inside brcmf_txfinalize()
drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c index c3a57e30c855..791757a3ec13 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c @@ -543,13 +543,13 @@ void brcmf_txfinalize(struct brcmf_if *ifp, struct sk_buff *txp, bool success)
Instead of checking ifp below you can simply do following here and be done with it:
if (!ifp) { brcmu_pkt_buf_free_skb(txp); return; }
eh = (struct ethhdr *)(txp->data); type = ntohs(eh->h_proto);
- if (type == ETH_P_PAE) {
- if (type == ETH_P_PAE && ifp) { atomic_dec(&ifp->pend_8021x_cnt); if (waitqueue_active(&ifp->pend_8021x_wait)) wake_up(&ifp->pend_8021x_wait); }
- if (!success)
- if (!success && ifp) ifp->ndev->stats.tx_errors++;
brcmu_pkt_buf_free_skb(txp);