[PATCH 5.4 079/367] wifi: ath9k: protect WMI command response buffer replacement with a lock

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5.4-stable review patch.  If anyone has any objections, please let me know.


From: Fedor Pchelkin <pchelkin@xxxxxxxxx>

[ Upstream commit 454994cfa9e4c18b6df9f78b60db8eadc20a6c25 ]

If ath9k_wmi_cmd() has exited with a timeout, it is possible that during
next ath9k_wmi_cmd() call the wmi_rsp callback for previous wmi command
writes to new wmi->cmd_rsp_buf and makes a completion. This results in an
invalid ath9k_wmi_cmd() return value.

Move the replacement of WMI command response buffer and length under
wmi_lock. Note that last_seq_id value is updated there, too.

Thus, the buffer cannot be written to by a belated wmi_rsp callback
because that path is properly rejected by the last_seq_id check.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Acked-by: Toke Høiland-Jørgensen <toke@xxxxxxx>
Signed-off-by: Kalle Valo <quic_kvalo@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230425192607.18015-2-pchelkin@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
 drivers/net/wireless/ath/ath9k/wmi.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/wmi.c b/drivers/net/wireless/ath/ath9k/wmi.c
index 96482ad23145c..dd8027b8af63e 100644
--- a/drivers/net/wireless/ath/ath9k/wmi.c
+++ b/drivers/net/wireless/ath/ath9k/wmi.c
@@ -280,7 +280,8 @@ int ath9k_wmi_connect(struct htc_target *htc, struct wmi *wmi,
 static int ath9k_wmi_cmd_issue(struct wmi *wmi,
 			       struct sk_buff *skb,
-			       enum wmi_cmd_id cmd, u16 len)
+			       enum wmi_cmd_id cmd, u16 len,
+			       u8 *rsp_buf, u32 rsp_len)
 	struct wmi_cmd_hdr *hdr;
 	unsigned long flags;
@@ -290,6 +291,11 @@ static int ath9k_wmi_cmd_issue(struct wmi *wmi,
 	hdr->seq_no = cpu_to_be16(++wmi->tx_seq_id);
 	spin_lock_irqsave(&wmi->wmi_lock, flags);
+	/* record the rsp buffer and length */
+	wmi->cmd_rsp_buf = rsp_buf;
+	wmi->cmd_rsp_len = rsp_len;
 	wmi->last_seq_id = wmi->tx_seq_id;
 	spin_unlock_irqrestore(&wmi->wmi_lock, flags);
@@ -330,11 +336,7 @@ int ath9k_wmi_cmd(struct wmi *wmi, enum wmi_cmd_id cmd_id,
 		goto out;
-	/* record the rsp buffer and length */
-	wmi->cmd_rsp_buf = rsp_buf;
-	wmi->cmd_rsp_len = rsp_len;
-	ret = ath9k_wmi_cmd_issue(wmi, skb, cmd_id, cmd_len);
+	ret = ath9k_wmi_cmd_issue(wmi, skb, cmd_id, cmd_len, rsp_buf, rsp_len);
 	if (ret)
 		goto out;

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