Date:   Tue, 30 Jan 2018 10:59:00 -0600
From:   Mario Limonciello <mario.limonciello@...l.com>
To:     dvhart@...radead.org, Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     pali.rohar@...il.com, LKML <linux-kernel@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org,
        Mario Limonciello <mario.limonciello@...l.com>
Subject: [PATCH] platform/x86: dell-laptop: Allocate buffer on heap rather than globally

There may be race conditions with multiple different functions working
on a module wide buffer causing one function to get the wrong results.

Suggested-by: Pali Rohar <pali.rohar@...il.com>
Signed-off-by: Mario Limonciello <mario.limonciello@...l.com>
---
 drivers/platform/x86/dell-laptop.c | 188 ++++++++++++++++++++-----------------
 1 file changed, 103 insertions(+), 85 deletions(-)

diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index fc2dfc8..ab58373 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -78,7 +78,6 @@ static struct platform_driver platform_driver = {
 	}
 };
 
-static struct calling_interface_buffer *buffer;
 static struct platform_device *platform_device;
 static struct backlight_device *dell_backlight_device;
 static struct rfkill *wifi_rfkill;
@@ -322,7 +321,8 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
 	{ }
 };
 
-static void dell_set_arguments(u32 arg0, u32 arg1, u32 arg2, u32 arg3)
+static void dell_set_arguments(struct calling_interface_buffer *buffer,
+			       u32 arg0, u32 arg1, u32 arg2, u32 arg3)
 {
 	memset(buffer, 0, sizeof(struct calling_interface_buffer));
 	buffer->input[0] = arg0;
@@ -331,7 +331,8 @@ static void dell_set_arguments(u32 arg0, u32 arg1, u32 arg2, u32 arg3)
 	buffer->input[3] = arg3;
 }
 
-static int dell_send_request(u16 class, u16 select)
+static int dell_send_request(struct calling_interface_buffer *buffer,
+			     u16 class, u16 select)
 {
 	int ret;
 
@@ -468,21 +469,22 @@ static int dell_rfkill_set(void *data, bool blocked)
 	int disable = blocked ? 1 : 0;
 	unsigned long radio = (unsigned long)data;
 	int hwswitch_bit = (unsigned long)data - 1;
+	struct calling_interface_buffer buffer;
 	int hwswitch;
 	int status;
 	int ret;
 
-	dell_set_arguments(0, 0, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	dell_set_arguments(&buffer, 0, 0, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
 	if (ret)
 		return ret;
-	status = buffer->output[1];
+	status = buffer.output[1];
 
-	dell_set_arguments(0x2, 0, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	dell_set_arguments(&buffer, 0x2, 0, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
 	if (ret)
 		return ret;
-	hwswitch = buffer->output[1];
+	hwswitch = buffer.output[1];
 
 	/* If the hardware switch controls this radio, and the hardware
 	   switch is disabled, always disable the radio */
@@ -490,8 +492,8 @@ static int dell_rfkill_set(void *data, bool blocked)
 	    (status & BIT(0)) && !(status & BIT(16)))
 		disable = 1;
 
-	dell_set_arguments(1 | (radio<<8) | (disable << 16), 0, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	dell_set_arguments(&buffer, 1 | (radio<<8) | (disable << 16), 0, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
 	return ret;
 }
 
@@ -500,9 +502,11 @@ static void dell_rfkill_update_sw_state(struct rfkill *rfkill, int radio,
 {
 	if (status & BIT(0)) {
 		/* Has hw-switch, sync sw_state to BIOS */
+		struct calling_interface_buffer buffer;
 		int block = rfkill_blocked(rfkill);
-		dell_set_arguments(1 | (radio << 8) | (block << 16), 0, 0, 0);
-		dell_send_request(CLASS_INFO, SELECT_RFKILL);
+		dell_set_arguments(&buffer,
+				   1 | (radio << 8) | (block << 16), 0, 0, 0);
+		dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
 	} else {
 		/* No hw-switch, sync BIOS state to sw_state */
 		rfkill_set_sw_state(rfkill, !!(status & BIT(radio + 16)));
@@ -519,21 +523,22 @@ static void dell_rfkill_update_hw_state(struct rfkill *rfkill, int radio,
 static void dell_rfkill_query(struct rfkill *rfkill, void *data)
 {
 	int radio = ((unsigned long)data & 0xF);
+	struct calling_interface_buffer buffer;
 	int hwswitch;
 	int status;
 	int ret;
 
-	dell_set_arguments(0, 0, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
-	status = buffer->output[1];
+	dell_set_arguments(&buffer, 0, 0, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
+	status = buffer.output[1];
 
 	if (ret != 0 || !(status & BIT(0))) {
 		return;
 	}
 
-	dell_set_arguments(0, 0x2, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
-	hwswitch = buffer->output[1];
+	dell_set_arguments(&buffer, 0, 0x2, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
+	hwswitch = buffer.output[1];
 
 	if (ret != 0)
 		return;
@@ -550,22 +555,23 @@ static struct dentry *dell_laptop_dir;
 
 static int dell_debugfs_show(struct seq_file *s, void *data)
 {
+	struct calling_interface_buffer buffer;
 	int hwswitch_state;
 	int hwswitch_ret;
 	int status;
 	int ret;
 
-	dell_set_arguments(0, 0, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	dell_set_arguments(&buffer, 0, 0, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
 	if (ret)
 		return ret;
-	status = buffer->output[1];
+	status = buffer.output[1];
 
-	dell_set_arguments(0, 0x2, 0, 0);
-	hwswitch_ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	dell_set_arguments(&buffer, 0, 0x2, 0, 0);
+	hwswitch_ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
 	if (hwswitch_ret)
 		return hwswitch_ret;
-	hwswitch_state = buffer->output[1];
+	hwswitch_state = buffer.output[1];
 
 	seq_printf(s, "return:\t%d\n", ret);
 	seq_printf(s, "status:\t0x%X\n", status);
@@ -646,22 +652,23 @@ static const struct file_operations dell_debugfs_fops = {
 
 static void dell_update_rfkill(struct work_struct *ignored)
 {
+	struct calling_interface_buffer buffer;
 	int hwswitch = 0;
 	int status;
 	int ret;
 
-	dell_set_arguments(0, 0, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
-	status = buffer->output[1];
+	dell_set_arguments(&buffer, 0, 0, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
+	status = buffer.output[1];
 
 	if (ret != 0)
 		return;
 
-	dell_set_arguments(0, 0x2, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
+	dell_set_arguments(&buffer, 0, 0x2, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
 
 	if (ret == 0 && (status & BIT(0)))
-		hwswitch = buffer->output[1];
+		hwswitch = buffer.output[1];
 
 	if (wifi_rfkill) {
 		dell_rfkill_update_hw_state(wifi_rfkill, 1, status, hwswitch);
@@ -719,6 +726,7 @@ static struct notifier_block dell_laptop_rbtn_notifier = {
 
 static int __init dell_setup_rfkill(void)
 {
+	struct calling_interface_buffer buffer;
 	int status, ret, whitelisted;
 	const char *product;
 
@@ -734,9 +742,9 @@ static int __init dell_setup_rfkill(void)
 	if (!force_rfkill && !whitelisted)
 		return 0;
 
-	dell_set_arguments(0, 0, 0, 0);
-	ret = dell_send_request(CLASS_INFO, SELECT_RFKILL);
-	status = buffer->output[1];
+	dell_set_arguments(&buffer, 0, 0, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_INFO, SELECT_RFKILL);
+	status = buffer.output[1];
 
 	/* dell wireless info smbios call is not supported */
 	if (ret != 0)
@@ -889,6 +897,7 @@ static void dell_cleanup_rfkill(void)
 
 static int dell_send_intensity(struct backlight_device *bd)
 {
+	struct calling_interface_buffer buffer;
 	struct calling_interface_token *token;
 	int ret;
 
@@ -896,17 +905,21 @@ static int dell_send_intensity(struct backlight_device *bd)
 	if (!token)
 		return -ENODEV;
 
-	dell_set_arguments(token->location, bd->props.brightness, 0, 0);
+	dell_set_arguments(&buffer,
+			   token->location, bd->props.brightness, 0, 0);
 	if (power_supply_is_system_supplied() > 0)
-		ret = dell_send_request(CLASS_TOKEN_WRITE, SELECT_TOKEN_AC);
+		ret = dell_send_request(&buffer,
+					CLASS_TOKEN_WRITE, SELECT_TOKEN_AC);
 	else
-		ret = dell_send_request(CLASS_TOKEN_WRITE, SELECT_TOKEN_BAT);
+		ret = dell_send_request(&buffer,
+					CLASS_TOKEN_WRITE, SELECT_TOKEN_BAT);
 
 	return ret;
 }
 
 static int dell_get_intensity(struct backlight_device *bd)
 {
+	struct calling_interface_buffer buffer;
 	struct calling_interface_token *token;
 	int ret;
 
@@ -914,14 +927,17 @@ static int dell_get_intensity(struct backlight_device *bd)
 	if (!token)
 		return -ENODEV;
 
-	dell_set_arguments(token->location, 0, 0, 0);
+	dell_set_arguments(&buffer, token->location, 0, 0, 0);
 	if (power_supply_is_system_supplied() > 0)
-		ret = dell_send_request(CLASS_TOKEN_READ, SELECT_TOKEN_AC);
+		ret = dell_send_request(&buffer,
+					CLASS_TOKEN_READ, SELECT_TOKEN_AC);
 	else
-		ret = dell_send_request(CLASS_TOKEN_READ, SELECT_TOKEN_BAT);
+		ret = dell_send_request(&buffer,
+					CLASS_TOKEN_READ, SELECT_TOKEN_BAT);
 
 	if (ret == 0)
-		ret = buffer->output[1];
+		ret = buffer.output[1];
+
 	return ret;
 }
 
@@ -1186,31 +1202,33 @@ static enum led_brightness kbd_led_level;
 
 static int kbd_get_info(struct kbd_info *info)
 {
+	struct calling_interface_buffer buffer;
 	u8 units;
 	int ret;
 
-	dell_set_arguments(0, 0, 0, 0);
-	ret = dell_send_request(CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
+	dell_set_arguments(&buffer, 0, 0, 0, 0);
+	ret = dell_send_request(&buffer,
+				CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
 	if (ret)
 		return ret;
 
-	info->modes = buffer->output[1] & 0xFFFF;
-	info->type = (buffer->output[1] >> 24) & 0xFF;
-	info->triggers = buffer->output[2] & 0xFF;
-	units = (buffer->output[2] >> 8) & 0xFF;
-	info->levels = (buffer->output[2] >> 16) & 0xFF;
+	info->modes = buffer.output[1] & 0xFFFF;
+	info->type = (buffer.output[1] >> 24) & 0xFF;
+	info->triggers = buffer.output[2] & 0xFF;
+	units = (buffer.output[2] >> 8) & 0xFF;
+	info->levels = (buffer.output[2] >> 16) & 0xFF;
 
 	if (quirks && quirks->kbd_led_levels_off_1 && info->levels)
 		info->levels--;
 
 	if (units & BIT(0))
-		info->seconds = (buffer->output[3] >> 0) & 0xFF;
+		info->seconds = (buffer.output[3] >> 0) & 0xFF;
 	if (units & BIT(1))
-		info->minutes = (buffer->output[3] >> 8) & 0xFF;
+		info->minutes = (buffer.output[3] >> 8) & 0xFF;
 	if (units & BIT(2))
-		info->hours = (buffer->output[3] >> 16) & 0xFF;
+		info->hours = (buffer.output[3] >> 16) & 0xFF;
 	if (units & BIT(3))
-		info->days = (buffer->output[3] >> 24) & 0xFF;
+		info->days = (buffer.output[3] >> 24) & 0xFF;
 
 	return ret;
 }
@@ -1270,31 +1288,34 @@ static int kbd_set_level(struct kbd_state *state, u8 level)
 
 static int kbd_get_state(struct kbd_state *state)
 {
+	struct calling_interface_buffer buffer;
 	int ret;
 
-	dell_set_arguments(0x1, 0, 0, 0);
-	ret = dell_send_request(CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
+	dell_set_arguments(&buffer, 0, 0, 0, 0);
+	ret = dell_send_request(&buffer,
+				CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
 	if (ret)
 		return ret;
 
-	state->mode_bit = ffs(buffer->output[1] & 0xFFFF);
+	state->mode_bit = ffs(buffer.output[1] & 0xFFFF);
 	if (state->mode_bit != 0)
 		state->mode_bit--;
 
-	state->triggers = (buffer->output[1] >> 16) & 0xFF;
-	state->timeout_value = (buffer->output[1] >> 24) & 0x3F;
-	state->timeout_unit = (buffer->output[1] >> 30) & 0x3;
-	state->als_setting = buffer->output[2] & 0xFF;
-	state->als_value = (buffer->output[2] >> 8) & 0xFF;
-	state->level = (buffer->output[2] >> 16) & 0xFF;
-	state->timeout_value_ac = (buffer->output[2] >> 24) & 0x3F;
-	state->timeout_unit_ac = (buffer->output[2] >> 30) & 0x3;
+	state->triggers = (buffer.output[1] >> 16) & 0xFF;
+	state->timeout_value = (buffer.output[1] >> 24) & 0x3F;
+	state->timeout_unit = (buffer.output[1] >> 30) & 0x3;
+	state->als_setting = buffer.output[2] & 0xFF;
+	state->als_value = (buffer.output[2] >> 8) & 0xFF;
+	state->level = (buffer.output[2] >> 16) & 0xFF;
+	state->timeout_value_ac = (buffer.output[2] >> 24) & 0x3F;
+	state->timeout_unit_ac = (buffer.output[2] >> 30) & 0x3;
 
 	return ret;
 }
 
 static int kbd_set_state(struct kbd_state *state)
 {
+	struct calling_interface_buffer buffer;
 	int ret;
 	u32 input1;
 	u32 input2;
@@ -1307,8 +1328,9 @@ static int kbd_set_state(struct kbd_state *state)
 	input2 |= (state->level & 0xFF) << 16;
 	input2 |= (state->timeout_value_ac & 0x3F) << 24;
 	input2 |= (state->timeout_unit_ac & 0x3) << 30;
-	dell_set_arguments(0x2, input1, input2, 0);
-	ret = dell_send_request(CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
+	dell_set_arguments(&buffer, 0x2, input1, input2, 0);
+	ret = dell_send_request(&buffer,
+				CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT);
 
 	return ret;
 }
@@ -1335,6 +1357,7 @@ static int kbd_set_state_safe(struct kbd_state *state, struct kbd_state *old)
 
 static int kbd_set_token_bit(u8 bit)
 {
+	struct calling_interface_buffer buffer;
 	struct calling_interface_token *token;
 	int ret;
 
@@ -1345,14 +1368,15 @@ static int kbd_set_token_bit(u8 bit)
 	if (!token)
 		return -EINVAL;
 
-	dell_set_arguments(token->location, token->value, 0, 0);
-	ret = dell_send_request(CLASS_TOKEN_WRITE, SELECT_TOKEN_STD);
+	dell_set_arguments(&buffer, token->location, token->value, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_TOKEN_WRITE, SELECT_TOKEN_STD);
 
 	return ret;
 }
 
 static int kbd_get_token_bit(u8 bit)
 {
+	struct calling_interface_buffer buffer;
 	struct calling_interface_token *token;
 	int ret;
 	int val;
@@ -1364,9 +1388,9 @@ static int kbd_get_token_bit(u8 bit)
 	if (!token)
 		return -EINVAL;
 
-	dell_set_arguments(token->location, 0, 0, 0);
-	ret = dell_send_request(CLASS_TOKEN_READ, SELECT_TOKEN_STD);
-	val = buffer->output[1];
+	dell_set_arguments(&buffer, token->location, 0, 0, 0);
+	ret = dell_send_request(&buffer, CLASS_TOKEN_READ, SELECT_TOKEN_STD);
+	val = buffer.output[1];
 
 	if (ret)
 		return ret;
@@ -2102,6 +2126,7 @@ static struct notifier_block dell_laptop_notifier = {
 
 int dell_micmute_led_set(int state)
 {
+	struct calling_interface_buffer buffer;
 	struct calling_interface_token *token;
 
 	if (state == 0)
@@ -2114,8 +2139,8 @@ int dell_micmute_led_set(int state)
 	if (!token)
 		return -ENODEV;
 
-	dell_set_arguments(token->location, token->value, 0, 0);
-	dell_send_request(CLASS_TOKEN_WRITE, SELECT_TOKEN_STD);
+	dell_set_arguments(&buffer, token->location, token->value, 0, 0);
+	dell_send_request(&buffer, CLASS_TOKEN_WRITE, SELECT_TOKEN_STD);
 
 	return state;
 }
@@ -2146,13 +2171,6 @@ static int __init dell_init(void)
 	if (ret)
 		goto fail_platform_device2;
 
-	buffer = kzalloc(sizeof(struct calling_interface_buffer), GFP_KERNEL);
-	if (!buffer) {
-		ret = -ENOMEM;
-		goto fail_buffer;
-	}
-
-
 	ret = dell_setup_rfkill();
 
 	if (ret) {
@@ -2177,10 +2195,13 @@ static int __init dell_init(void)
 
 	token = dell_smbios_find_token(BRIGHTNESS_TOKEN);
 	if (token) {
-		dell_set_arguments(token->location, 0, 0, 0);
-		ret = dell_send_request(CLASS_TOKEN_READ, SELECT_TOKEN_AC);
+		struct calling_interface_buffer buffer;
+
+		dell_set_arguments(&buffer, token->location, 0, 0, 0);
+		ret = dell_send_request(&buffer,
+					CLASS_TOKEN_READ, SELECT_TOKEN_AC);
 		if (ret)
-			max_intensity = buffer->output[3];
+			max_intensity = buffer.output[3];
 	}
 
 	if (max_intensity) {
@@ -2214,8 +2235,6 @@ static int __init dell_init(void)
 fail_get_brightness:
 	backlight_device_unregister(dell_backlight_device);
 fail_backlight:
-	kfree(buffer);
-fail_buffer:
 	dell_cleanup_rfkill();
 fail_rfkill:
 	platform_device_del(platform_device);
@@ -2235,7 +2254,6 @@ static void __exit dell_exit(void)
 		touchpad_led_exit();
 	kbd_led_exit();
 	backlight_device_unregister(dell_backlight_device);
-	kfree(buffer);
 	dell_cleanup_rfkill();
 	if (platform_device) {
 		platform_device_unregister(platform_device);
-- 
2.7.4

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