[PATCH v3] wifi: wilc1000: fix DMA on stack objects

[<Ajay.Kathat@microchip.com>]

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@kernel.org>
Suggested-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
---
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@walle.cc/ 

changes since v2:
	- use 'bool' datatype instead of 'u8' for 'use_global_buf'
	- add size fit check before copying to 'cmd53_buf' buffer in
	  wilc_sdio_cmd53() 

changes since v1:
	- add 'use_global_buf' variable to know when to use bounce buffer
	- remove unnecessary goto label
	- dynamically allocate 'vmm_table'

 .../net/wireless/microchip/wilc1000/netdev.h  |  1 +
 .../net/wireless/microchip/wilc1000/sdio.c    | 39 ++++++++++++++++---
 .../net/wireless/microchip/wilc1000/wlan.c    | 15 ++++++-
 3 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/microchip/wilc1000/netdev.h b/drivers/net/wireless/microchip/wilc1000/netdev.h
index 43c085c74b7a..bb1a315a7b7e 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;
 
 	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..7390f94cd4ca 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 {
@@ -47,6 +48,7 @@ struct sdio_cmd53 {
 	u32 count:		9;
 	u8 *buffer;
 	u32 block_size;
+	bool use_global_buf;
 };
 
 static const struct wilc_hif_func wilc_hif_sdio;
@@ -91,6 +93,8 @@ static int wilc_sdio_cmd53(struct wilc *wilc, struct sdio_cmd53 *cmd)
 {
 	struct sdio_func *func = container_of(wilc->dev, struct sdio_func, dev);
 	int size, ret;
+	struct wilc_sdio *sdio_priv = wilc->bus_data;
+	u8 *buf = cmd->buffer;
 
 	sdio_claim_host(func);
 
@@ -101,12 +105,23 @@ static int wilc_sdio_cmd53(struct wilc *wilc, struct sdio_cmd53 *cmd)
 	else
 		size = cmd->count;
 
+	if (cmd->use_global_buf) {
+		if (size > sizeof(u32))
+			return -EINVAL;
+
+		buf = sdio_priv->cmd53_buf;
+	}
+
 	if (cmd->read_write) {  /* write */
-		ret = sdio_memcpy_toio(func, cmd->address,
-				       (void *)cmd->buffer, size);
+		if (cmd->use_global_buf)
+			memcpy(buf, cmd->buffer, size);
+
+		ret = sdio_memcpy_toio(func, cmd->address, buf, size);
 	} else {        /* read */
-		ret = sdio_memcpy_fromio(func, (void *)cmd->buffer,
-					 cmd->address,  size);
+		ret = sdio_memcpy_fromio(func, buf, cmd->address, size);
+
+		if (cmd->use_global_buf)
+			memcpy(cmd->buffer, buf, size);
 	}
 
 	sdio_release_host(func);
@@ -128,6 +143,12 @@ 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)
@@ -161,6 +182,7 @@ static int wilc_sdio_probe(struct sdio_func *func,
 	irq_dispose_mapping(wilc->dev_irq_num);
 	wilc_netdev_cleanup(wilc);
 free:
+	kfree(sdio_priv->cmd53_buf);
 	kfree(sdio_priv);
 	return ret;
 }
@@ -172,6 +194,7 @@ 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 +398,9 @@ 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.count = sizeof(u32);
 		cmd.buffer = (u8 *)&data;
+		cmd.use_global_buf = true;
 		cmd.block_size = sdio_priv->block_size;
 		ret = wilc_sdio_cmd53(wilc, &cmd);
 		if (ret)
@@ -414,6 +438,7 @@ static int wilc_sdio_write(struct wilc *wilc, u32 addr, u8 *buf, u32 size)
 	nblk = size / block_size;
 	nleft = size % block_size;
 
+	cmd.use_global_buf = false;
 	if (nblk > 0) {
 		cmd.block_mode = 1;
 		cmd.increment = 1;
@@ -492,8 +517,9 @@ 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.count = sizeof(u32);
 		cmd.buffer = (u8 *)data;
+		cmd.use_global_buf = true;
 
 		cmd.block_size = sdio_priv->block_size;
 		ret = wilc_sdio_cmd53(wilc, &cmd);
@@ -535,6 +561,7 @@ static int wilc_sdio_read(struct wilc *wilc, u32 addr, u8 *buf, u32 size)
 	nblk = size / block_size;
 	nleft = size % block_size;
 
+	cmd.use_global_buf = false;
 	if (nblk > 0) {
 		cmd.block_mode = 1;
 		cmd.increment = 1;
diff --git a/drivers/net/wireless/microchip/wilc1000/wlan.c b/drivers/net/wireless/microchip/wilc1000/wlan.c
index 947d9a0a494e..58bbf50081e4 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;
@@ -1252,6 +1252,8 @@ void wilc_wlan_cleanup(struct net_device *dev)
 	while ((rqe = wilc_wlan_rxq_remove(wilc)))
 		kfree(rqe);
 
+	kfree(wilc->vmm_table);
+	wilc->vmm_table = NULL;
 	kfree(wilc->rx_buffer);
 	wilc->rx_buffer = NULL;
 	kfree(wilc->tx_buffer);
@@ -1489,6 +1491,14 @@ int wilc_wlan_init(struct net_device *dev)
 			goto fail;
 	}
 
+	if (!wilc->vmm_table)
+		wilc->vmm_table = kzalloc(WILC_VMM_TBL_SIZE, GFP_KERNEL);
+
+	if (!wilc->vmm_table) {
+		ret = -ENOBUFS;
+		goto fail;
+	}
+
 	if (!wilc->tx_buffer)
 		wilc->tx_buffer = kmalloc(WILC_TX_BUFF_SIZE, GFP_KERNEL);
 
@@ -1513,7 +1523,8 @@ int wilc_wlan_init(struct net_device *dev)
 	return 0;
 
 fail:
-
+	kfree(wilc->vmm_table);
+	wilc->vmm_table = NULL;
 	kfree(wilc->rx_buffer);
 	wilc->rx_buffer = NULL;
 	kfree(wilc->tx_buffer);
-- 
2.34.1