wifi: rsi: Fix memory corruption due to not set vif driver data size

wifi: rsi: Fix memory corruption due to not set vif driver data size

The struct ieee80211_vif contains trailing space for vif driver data,
when struct ieee80211_vif is allocated, the total memory size that is
allocated is sizeof(struct ieee80211_vif) + size of vif driver data.
The size of vif driver data is set by each WiFi driver as needed.

The RSI911x driver does not set vif driver data size, no trailing space
for vif driver data is therefore allocated past struct ieee80211_vif .
The RSI911x driver does however use the vif driver data to store its
vif driver data structure "struct vif_priv". An access to vif->drv_priv
leads to access out of struct ieee80211_vif bounds and corruption of
some memory.

In case of the failure observed locally, rsi_mac80211_add_interface()
would write struct vif_priv *vif_info = (struct vif_priv *)vif->drv_priv;
vif_info->vap_id = vap_idx. This write corrupts struct fq_tin member
struct list_head new_flows . The flow = list_first_entry(head, struct
fq_flow, flowchain); in fq_tin_reset() then reports non-NULL bogus
address, which when accessed causes a crash.

The trigger is very simple, boot the machine with init=/bin/sh , mount
devtmpfs, sysfs, procfs, and then do "ip link set wlan0 up", "sleep 1",
"ip link set wlan0 down" and the crash occurs.

Fix this by setting the correct size of vif driver data, which is the
size of "struct vif_priv", so that memory is allocated and the driver
can store its driver data in it, instead of corrupting memory around
it.

Cc: stable@vger.kernel.org
Fixes: dad0d04fa7ba ("rsi: Add RS9113 wireless driver")
Signed-off-by: Marek Vasut <marex@nabladev.com>
Link: https://patch.msgid.link/20260109235817.150330-1-marex@nabladev.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>