On January 15, 2025 4:16:58 PM Kalle Valo <kvalo@xxxxxxxxxx> wrote:
Marcel Hamer <marcel.hamer@xxxxxxxxxxxxx> 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.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Marcel Hamer <marcel.hamer@xxxxxxxxxxxxx>
Link:
https://lore.kernel.org/all/b519e746-ddfd-421f-d897-7620d229e4b2@xxxxxxxxx/
If you submit v3, please add 'wifi:'.
ERROR: 'wifi:' prefix missing: '[PATCH v2] brcmfmac: NULL pointer
dereference on tx statistic update'
While at it maybe rephrase the subject to:
wifi: brcmfmac: fix NULL pointer dereference in brcmf_txfinalize()
Regards,
Arend
