During our testing of WFM200 module over SDIO on i.MX6Q-based platform,
we discovered a memory corruption on the system, tracing back to the wfx
driver. Using kfence, it was possible to trace it back to the root
cause, which is hw->max_rates set to 8 in wfx_init_common,
while the maximum defined by IEEE80211_TX_TABLE_SIZE is 4.

This causes array out-of-bounds writes during updates of the rate table,
as seen below:

BUG: KFENCE: memory corruption in kfree_rcu_work+0x320/0x36c

Corrupted memory at 0xe0a4ffe0 [ 0x03 0x03 0x03 0x03 0x01 0x00 0x00
0x02 0x02 0x02 0x09 0x00 0x21 0xbb 0xbb 0xbb ] (in kfence-#81):
kfree_rcu_work+0x320/0x36c
process_one_work+0x3ec/0x920
worker_thread+0x60/0x7a4
kthread+0x174/0x1b4
ret_from_fork+0x14/0x2c
0x0

kfence-#81: 0xe0a4ffc0-0xe0a4ffdf, size=32, cache=kmalloc-64

allocated by task 297 on cpu 0 at 631.039555s:
minstrel_ht_update_rates+0x38/0x2b0 [mac80211]
rate_control_tx_status+0xb4/0x148 [mac80211]
ieee80211_tx_status_ext+0x364/0x1030 [mac80211]
ieee80211_tx_status+0xe0/0x118 [mac80211]
ieee80211_tasklet_handler+0xb0/0xe0 [mac80211]
tasklet_action_common.constprop.0+0x11c/0x148
__do_softirq+0x1a4/0x61c
irq_exit+0xcc/0x104
call_with_stack+0x18/0x20
__irq_svc+0x80/0xb0
wq_worker_sleeping+0x10/0x100
wq_worker_sleeping+0x10/0x100
schedule+0x50/0xe0
schedule_timeout+0x2e0/0x474
wait_for_completion+0xdc/0x1ec
mmc_wait_for_req_done+0xc4/0xf8
mmc_io_rw_extended+0x3b4/0x4ec
sdio_io_rw_ext_helper+0x290/0x384
sdio_memcpy_toio+0x30/0x38
wfx_sdio_copy_to_io+0x88/0x108 [wfx]
wfx_data_write+0x88/0x1f0 [wfx]
bh_work+0x1c8/0xcc0 [wfx]
process_one_work+0x3ec/0x920
worker_thread+0x60/0x7a4
kthread+0x174/0x1b4
ret_from_fork+0x14/0x2c 0x0

After discussion on the wireless mailing list it was clarified
that the issue has been introduced by:
commit ee0e16ab ("mac80211: minstrel_ht: fill all requested rates")
and fix shall be in minstrel_ht_update_rates in rc80211_minstrel_ht.c.

Fixes: ee0e16ab ("mac80211: minstrel_ht: fill all requested rates")
Link: https://lore.kernel.org/all/12e5adcd-8aed-f0f7-70cc-4fb7b656b829@camlingroup.com/
Link: https://lore.kernel.org/linux-wireless/20220915131445.30600-1-lech.perczak@camlingroup.com/
Cc: Jérôme Pouiller <jerome.pouiller@silabs.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Peter Seiderer <ps.report@gmx.net>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Krzysztof Drobiński <krzysztof.drobinski@camlingroup.com>,
Signed-off-by: Paweł Lenkow <pawel.lenkow@camlingroup.com>
Signed-off-by: Lech Perczak <lech.perczak@camlingroup.com>
Reviewed-by: Peter Seiderer <ps.report@gmx.net>
Reviewed-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Acked-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>