[PATCH AUTOSEL 4.19 16/25] wifi: ath10k: reset pointer after memory free to avoid potential use-after-free

[Sasha Levin]

From: Wen Gong <quic_wgong at quicinc.com>

[ Upstream commit 1e1cb8e0b73e6f39a9d4a7a15d940b1265387eb5 ]

When running suspend test, kernel crash happened in ath10k, and it is
fixed by commit b72a4aff947b ("ath10k: skip ath10k_halt during suspend
for driver state RESTARTING").

Currently the crash is fixed, but as a common code style, it is better
to set the pointer to NULL after memory is free.

This is to address the code style and it will avoid potential bug of
use-after-free.

Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00110-QCARMSWP-1
Signed-off-by: Wen Gong <quic_wgong at quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo at quicinc.com>
Link: https://lore.kernel.org/r/20220505092248.787-1-quic_wgong@quicinc.com
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/net/wireless/ath/ath10k/htt_rx.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c
index 0a7551dc0f94..68728cba6df3 100644
--- a/drivers/net/wireless/ath/ath10k/htt_rx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
@@ -302,12 +302,16 @@ void ath10k_htt_rx_free(struct ath10k_htt *htt)
 			  ath10k_htt_get_vaddr_ring(htt),
 			  htt->rx_ring.base_paddr);
 
+	ath10k_htt_config_paddrs_ring(htt, NULL);
+
 	dma_free_coherent(htt->ar->dev,
 			  sizeof(*htt->rx_ring.alloc_idx.vaddr),
 			  htt->rx_ring.alloc_idx.vaddr,
 			  htt->rx_ring.alloc_idx.paddr);
+	htt->rx_ring.alloc_idx.vaddr = NULL;
 
 	kfree(htt->rx_ring.netbufs_ring);
+	htt->rx_ring.netbufs_ring = NULL;
 }
 
 static inline struct sk_buff *ath10k_htt_rx_netbuf_pop(struct ath10k_htt *htt)
@@ -641,8 +645,10 @@ int ath10k_htt_rx_alloc(struct ath10k_htt *htt)
 			  ath10k_htt_get_rx_ring_size(htt),
 			  vaddr_ring,
 			  htt->rx_ring.base_paddr);
+	ath10k_htt_config_paddrs_ring(htt, NULL);
 err_dma_ring:
 	kfree(htt->rx_ring.netbufs_ring);
+	htt->rx_ring.netbufs_ring = NULL;
 err_netbuf:
 	return -ENOMEM;
 }
-- 
2.35.1