[SRU][F][PATCH v2 0/1] wifi: ath10k: avoid NULL pointer error during sdio remove

[Abdur Rahman]

From: Kang Yang <quic_kangyang at quicinc.com>

When running 'rmmod ath10k', ath10k_sdio_remove() will free sdio
workqueue by destroy_workqueue(). But if CONFIG_INIT_ON_FREE_DEFAULT_ON
is set to yes, kernel panic will happen:
Call trace:
 destroy_workqueue+0x1c/0x258
 ath10k_sdio_remove+0x84/0x94
 sdio_bus_remove+0x50/0x16c
 device_release_driver_internal+0x188/0x25c
 device_driver_detach+0x20/0x2c

This is because during 'rmmod ath10k', ath10k_sdio_remove() will call
ath10k_core_destroy() before destroy_workqueue(). wiphy_dev_release()
will finally be called in ath10k_core_destroy(). This function will free
struct cfg80211_registered_device *rdev and all its members, including
wiphy, dev and the pointer of sdio workqueue. Then the pointer of sdio
workqueue will be set to NULL due to CONFIG_INIT_ON_FREE_DEFAULT_ON.

After device release, destroy_workqueue() will use NULL pointer then the
kernel panic happen.

Call trace:
ath10k_sdio_remove
  ->ath10k_core_unregister
    ……
    ->ath10k_core_stop
      ->ath10k_hif_stop
        ->ath10k_sdio_irq_disable
    ->ath10k_hif_power_down
      ->del_timer_sync(&ar_sdio->sleep_timer)
  ->ath10k_core_destroy
    ->ath10k_mac_destroy
      ->ieee80211_free_hw
        ->wiphy_free
    ……
          ->wiphy_dev_release
  ->destroy_workqueue

Need to call destroy_workqueue() before ath10k_core_destroy(), free
the work queue buffer first and then free pointer of work queue by
ath10k_core_destroy(). This order matches the error path order in
ath10k_sdio_probe().

No work will be queued on sdio workqueue between it is destroyed and
ath10k_core_destroy() is called. Based on the call_stack above, the
reason is:
Only ath10k_sdio_sleep_timer_handler(), ath10k_sdio_hif_tx_sg() and
ath10k_sdio_irq_disable() will queue work on sdio workqueue.
Sleep timer will be deleted before ath10k_core_destroy() in
ath10k_hif_power_down().
ath10k_sdio_irq_disable() only be called in ath10k_hif_stop().
ath10k_core_unregister() will call ath10k_hif_power_down() to stop hif
bus, so ath10k_sdio_hif_tx_sg() won't be called anymore.

Tested-on: QCA6174 hw3.2 SDIO WLAN.RMH.4.4.1-00189

Signed-off-by: Kang Yang <quic_kangyang at quicinc.com>
Tested-by: David Ruth <druth at chromium.org>
Reviewed-by: David Ruth <druth at chromium.org>
Link: https://patch.msgid.link/20241008022246.1010-1-quic_kangyang@quicinc.com
Signed-off-by: Jeff Johnson <quic_jjohnson at quicinc.com>
(backported from commit 95c38953cb1ecf40399a676a1f85dfe2b5780a9a 6.14.y)
[maskedarray: context changes were resolved. An additional function 
'flush_workqueue' appears in the context. The fix was verified to be 
valid still. Hence, the context was adjusted to apply the fix commit.]
CVE-2024-56599
Signed-off-by: Abdur Rahman <abdur.rahman at canonical.com>
---
 drivers/net/wireless/ath/ath10k/sdio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/sdio.c b/drivers/net/wireless/ath/ath10k/sdio.c
index 24b1927a0751..692125495d6a 100644
--- a/drivers/net/wireless/ath/ath10k/sdio.c
+++ b/drivers/net/wireless/ath/ath10k/sdio.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2004-2011 Atheros Communications Inc.
  * Copyright (c) 2011-2012,2017 Qualcomm Atheros, Inc.
  * Copyright (c) 2016-2017 Erik Stromdahl <erik.stromdahl at gmail.com>
+ * Copyright (c) 2022-2024 Qualcomm Innovation Center, Inc. All rights reserved.
  */
 
 #include <linux/module.h>
@@ -2123,10 +2124,11 @@ static void ath10k_sdio_remove(struct sdio_func *func)
 		   func->num, func->vendor, func->device);
 
 	ath10k_core_unregister(ar);
-	ath10k_core_destroy(ar);
 
 	flush_workqueue(ar_sdio->workqueue);
 	destroy_workqueue(ar_sdio->workqueue);
+
+	ath10k_core_destroy(ar);
 }
 
 static const struct sdio_device_id ath10k_sdio_devices[] = {
-- 
2.34.1