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

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Message-Id: <20221009222436.1219411-16-sashal@kernel.org>
Date:   Sun,  9 Oct 2022 18:24:21 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Wen Gong <quic_wgong@...cinc.com>,
        Kalle Valo <quic_kvalo@...cinc.com>,
        Sasha Levin <sashal@...nel.org>, kvalo@...nel.org,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, ath10k@...ts.infradead.org,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 16/25] wifi: ath10k: reset pointer after memory free to avoid potential use-after-free

From: Wen Gong <quic_wgong@...cinc.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@...cinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@...cinc.com>
Link: https://lore.kernel.org/r/20220505092248.787-1-quic_wgong@quicinc.com
Signed-off-by: Sasha Levin <sashal@...nel.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