[PATCH v4 2/2] wifi: ath12k: fix warning when unbinding

[Jose Ignacio Tornos Martinez <jtornosm@redhat.com>]

If there is an error during some initialization related to firmware,
the buffers dp->tx_ring[i].tx_status are released.
However this is released again when the device is unbinded (ath12k_pci),
and we get:
WARNING: CPU: 0 PID: 2098 at mm/slub.c:4689 free_large_kmalloc+0x4d/0x80
Call Trace:
free_large_kmalloc
ath12k_dp_free
ath12k_core_deinit
ath12k_pci_remove
...

The issue is always reproducible from a VM because the MSI addressing
initialization is failing.

In order to fix the issue, just set the buffers to NULL after releasing in
order to avoid the double free.

cc: stable@vger.kernel.org
Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
v4:
  - Send with cover letter to get reference with 1/2
v3: https://lore.kernel.org/linux-wireless/20241017074854.176765-1-jtornosm@redhat.com/
v2: https://lore.kernel.org/linux-wireless/20241016123722.206899-1-jtornosm@redhat.com/
v1: https://lore.kernel.org/linux-wireless/20241010175102.207324-3-jtornosm@redhat.com/

 drivers/net/wireless/ath/ath12k/dp.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath12k/dp.c b/drivers/net/wireless/ath/ath12k/dp.c
index 789d430e4455..15061782a2df 100644
--- a/drivers/net/wireless/ath/ath12k/dp.c
+++ b/drivers/net/wireless/ath/ath12k/dp.c
@@ -1277,8 +1277,10 @@ void ath12k_dp_free(struct ath12k_base *ab)
 
 	ath12k_dp_rx_reo_cmd_list_cleanup(ab);
 
-	for (i = 0; i < ab->hw_params->max_tx_ring; i++)
+	for (i = 0; i < ab->hw_params->max_tx_ring; i++) {
 		kfree(dp->tx_ring[i].tx_status);
+		dp->tx_ring[i].tx_status = NULL;
+	}
 
 	ath12k_dp_rx_free(ab);
 	/* Deinit any SOC level resource */
-- 
2.47.0