Re: [PATCH] mac80211: fix memory corruption in minstrel_ht_update_rates()

[Peter Seiderer <ps.report@gmx.net>]

On Mon, 19 Sep 2022 17:01:35 +0200, Lech Perczak <lech.perczak@camlingroup.com> wrote:

> From: Paweł Lenkow <pawel.lenkow@camlingroup.com>
> 
> 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 ee0e16ab756a ("mac80211: minstrel_ht: fill all requested rates")
> and fix shall be in minstrel_ht_update_rates in rc80211_minstrel_ht.c.
> 
> Fixes: ee0e16ab756a ("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>

Needs to be applied to 5.19 and 6.0...

Regards,
Peter

> ---
>  net/mac80211/rc80211_minstrel_ht.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
> index 5f27e6746762..788a82f9c74d 100644
> --- a/net/mac80211/rc80211_minstrel_ht.c
> +++ b/net/mac80211/rc80211_minstrel_ht.c
> @@ -10,6 +10,7 @@
>  #include <linux/random.h>
>  #include <linux/moduleparam.h>
>  #include <linux/ieee80211.h>
> +#include <linux/minmax.h>
>  #include <net/mac80211.h>
>  #include "rate.h"
>  #include "sta_info.h"
> @@ -1550,6 +1551,7 @@ minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
>  {
>  	struct ieee80211_sta_rates *rates;
>  	int i = 0;
> +	int max_rates = min_t(int, mp->hw->max_rates, IEEE80211_TX_RATE_TABLE_SIZE);
>  
>  	rates = kzalloc(sizeof(*rates), GFP_ATOMIC);
>  	if (!rates)
> @@ -1559,10 +1561,10 @@ minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
>  	minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[0]);
>  
>  	/* Fill up remaining, keep one entry for max_probe_rate */
> -	for (; i < (mp->hw->max_rates - 1); i++)
> +	for (; i < (max_rates - 1); i++)
>  		minstrel_ht_set_rate(mp, mi, rates, i, mi->max_tp_rate[i]);
>  
> -	if (i < mp->hw->max_rates)
> +	if (i < max_rates)
>  		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
>  
>  	if (i < IEEE80211_TX_RATE_TABLE_SIZE)