[PATCH] wifi: wilc1000: fix DMA on stack objects

[<Ajay.Kathat@xxxxxxxxxxxxx>]

From: Ajay Singh <ajay.kathat@xxxxxxxxxxxxx>

Sometimes 'wilc_sdio_cmd53' is called with addresses pointing to an
object on the stack. Use dynamically allocated memory for cmd53 instead
of stack address which is not DMA'able.

Fixes: 5625f965d764 ("wilc1000: move wilc driver out of staging")
Reported-by: Michael Walle <mwalle@xxxxxxxxxx>
Suggested-by: Michael Walle <mwalle@xxxxxxxxxx>
Signed-off-by: Ajay Singh <ajay.kathat@xxxxxxxxxxxxx>
---

This patch is created based on [1] and changes are done as discussed in
the same thread.

[1]. https://patchwork.kernel.org/project/linux-wireless/patch/20220728152037.386543-1-michael@xxxxxxxx/ 

 .../net/wireless/microchip/wilc1000/netdev.h  |  1 +
 .../net/wireless/microchip/wilc1000/sdio.c    | 23 +++++++++++++++----
 .../net/wireless/microchip/wilc1000/wlan.c    |  2 +-
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/microchip/wilc1000/netdev.h b/drivers/net/wireless/microchip/wilc1000/netdev.h
index 43c085c74b7a..2137ef294953 100644
--- a/drivers/net/wireless/microchip/wilc1000/netdev.h
+++ b/drivers/net/wireless/microchip/wilc1000/netdev.h
@@ -245,6 +245,7 @@ struct wilc {
 	u8 *rx_buffer;
 	u32 rx_buffer_offset;
 	u8 *tx_buffer;
+	u32 vmm_table[WILC_VMM_TBL_SIZE];
 
 	struct txq_handle txq[NQUEUES];
 	int txq_entries;
diff --git a/drivers/net/wireless/microchip/wilc1000/sdio.c b/drivers/net/wireless/microchip/wilc1000/sdio.c
index 600cc57e9da2..8bb0b8e189af 100644
--- a/drivers/net/wireless/microchip/wilc1000/sdio.c
+++ b/drivers/net/wireless/microchip/wilc1000/sdio.c
@@ -28,6 +28,7 @@ struct wilc_sdio {
 	u32 block_size;
 	bool isinit;
 	int has_thrpt_enh3;
+	u8 *cmd53_buf;
 };
 
 struct sdio_cmd52 {
@@ -128,10 +129,16 @@ static int wilc_sdio_probe(struct sdio_func *func,
 	if (!sdio_priv)
 		return -ENOMEM;
 
+	sdio_priv->cmd53_buf = kzalloc(sizeof(u32), GFP_KERNEL);
+	if (!sdio_priv->cmd53_buf) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
 	ret = wilc_cfg80211_init(&wilc, &func->dev, WILC_HIF_SDIO,
 				 &wilc_hif_sdio);
 	if (ret)
-		goto free;
+		goto free_buffer;
 
 	if (IS_ENABLED(CONFIG_WILC1000_HW_OOB_INTR)) {
 		struct device_node *np = func->card->dev.of_node;
@@ -160,6 +167,8 @@ static int wilc_sdio_probe(struct sdio_func *func,
 dispose_irq:
 	irq_dispose_mapping(wilc->dev_irq_num);
 	wilc_netdev_cleanup(wilc);
+free_buffer:
+	kfree(sdio_priv->cmd53_buf);
 free:
 	kfree(sdio_priv);
 	return ret;
@@ -172,6 +181,7 @@ static void wilc_sdio_remove(struct sdio_func *func)
 
 	clk_disable_unprepare(wilc->rtc_clk);
 	wilc_netdev_cleanup(wilc);
+	kfree(sdio_priv->cmd53_buf);
 	kfree(sdio_priv);
 }
 
@@ -375,8 +385,10 @@ static int wilc_sdio_write_reg(struct wilc *wilc, u32 addr, u32 data)
 		cmd.address = WILC_SDIO_FBR_DATA_REG;
 		cmd.block_mode = 0;
 		cmd.increment = 1;
-		cmd.count = 4;
-		cmd.buffer = (u8 *)&data;
+		cmd.count = sizeof(u32);
+		/* copy to a bounce buffer to avoid use of stack variable */
+		memcpy(sdio_priv->cmd53_buf, &data, sizeof(u32));
+		cmd.buffer = sdio_priv->cmd53_buf;
 		cmd.block_size = sdio_priv->block_size;
 		ret = wilc_sdio_cmd53(wilc, &cmd);
 		if (ret)
@@ -492,8 +504,8 @@ static int wilc_sdio_read_reg(struct wilc *wilc, u32 addr, u32 *data)
 		cmd.address = WILC_SDIO_FBR_DATA_REG;
 		cmd.block_mode = 0;
 		cmd.increment = 1;
-		cmd.count = 4;
-		cmd.buffer = (u8 *)data;
+		cmd.count = sizeof(u32);
+		cmd.buffer = sdio_priv->cmd53_buf;
 
 		cmd.block_size = sdio_priv->block_size;
 		ret = wilc_sdio_cmd53(wilc, &cmd);
@@ -502,6 +514,7 @@ static int wilc_sdio_read_reg(struct wilc *wilc, u32 addr, u32 *data)
 				"Failed cmd53, read reg (%08x)...\n", addr);
 			return ret;
 		}
+		memcpy(data, sdio_priv->cmd53_buf, sizeof(u32));
 	}
 
 	le32_to_cpus(data);
diff --git a/drivers/net/wireless/microchip/wilc1000/wlan.c b/drivers/net/wireless/microchip/wilc1000/wlan.c
index 947d9a0a494e..0576d865c603 100644
--- a/drivers/net/wireless/microchip/wilc1000/wlan.c
+++ b/drivers/net/wireless/microchip/wilc1000/wlan.c
@@ -714,7 +714,7 @@ int wilc_wlan_handle_txq(struct wilc *wilc, u32 *txq_count)
 	int ret = 0;
 	int counter;
 	int timeout;
-	u32 vmm_table[WILC_VMM_TBL_SIZE];
+	u32 *vmm_table = wilc->vmm_table;
 	u8 ac_pkt_num_to_chip[NQUEUES] = {0, 0, 0, 0};
 	const struct wilc_hif_func *func;
 	int srcu_idx;
-- 
2.34.1