ALSA: usb-audio: Relax __free() variable declarations

[ Upstream commit 03f705b9ca58b91c6dffe64875ea3d9a38cad9b5 ]

We used to have a variable declaration with __free() initialized with
NULL.  This was to keep the old coding style rule, but recently it's
relaxed and rather recommends to follow the new rule to declare in
place of use for __free() -- which avoids potential deadlocks or UAFs
with nested cleanups.

Although the current code has no bug, per se, let's follow the new
standard and move the declaration to the place of assignment (or
directly assign the allocated result) instead of NULL initializations.

Note that there are still a few remaining __free(kfree) with NULL
initializations; they are because of the code complexity (the data
size calculation).

Fixes: 43d4940c944c ("ALSA: usb: scarlett2: Clean ups with guard() and __free()")
Fixes: 46757a3e7d50 ("ALSA: FCP: Add Focusrite Control Protocol driver")
Fixes: f7d306b47a24 ("ALSA: usb-audio: Fix a DMA to stack memory bug")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20251216140634.171890-12-tiwai@suse.de
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 10 insertions, 11 deletions

diff --git a/sound/usb/mixer_scarlett2.c b/sound/usb/mixer_scarlett2.c
index bef8c9e544dd..88b7e42d159e 100644
--- a/sound/usb/mixer_scarlett2.c
+++ b/sound/usb/mixer_scarlett2.c
@@ -2377,18 +2377,18 @@ static int scarlett2_usb(
 {
 	struct scarlett2_data *private = mixer->private_data;
 	struct usb_device *dev = mixer->chip->dev;
-	struct scarlett2_usb_packet *req __free(kfree) = NULL;
-	struct scarlett2_usb_packet *resp __free(kfree) = NULL;
-	size_t req_buf_size = struct_size(req, data, req_size);
-	size_t resp_buf_size = struct_size(resp, data, resp_size);
 	int retries = 0;
 	const int max_retries = 5;
 	int err;
 
+	struct scarlett2_usb_packet *req __free(kfree) = NULL;
+	size_t req_buf_size = struct_size(req, data, req_size);
 	req = kmalloc(req_buf_size, GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;
 
+	struct scarlett2_usb_packet *resp __free(kfree) = NULL;
+	size_t resp_buf_size = struct_size(resp, data, resp_size);
 	resp = kmalloc(resp_buf_size, GFP_KERNEL);
 	if (!resp)
 		return -ENOMEM;
@@ -3919,9 +3919,9 @@ static int scarlett2_input_select_ctl_info(
 	struct scarlett2_data *private = mixer->private_data;
 	int inputs = private->info->gain_input_count;
 	int i, err;
-	char **values __free(kfree) = NULL;
+	char **values __free(kfree) =
+		kcalloc(inputs, sizeof(char *), GFP_KERNEL);
 
-	values = kcalloc(inputs, sizeof(char *), GFP_KERNEL);
 	if (!values)
 		return -ENOMEM;
 
@@ -9083,8 +9083,6 @@ static long scarlett2_hwdep_read(struct snd_hwdep *hw,
 		__le32 len;
 	} __packed req;
 
-	u8 *resp __free(kfree) = NULL;
-
 	/* Flash segment must first be selected */
 	if (private->flash_write_state != SCARLETT2_FLASH_WRITE_STATE_SELECTED)
 		return -EINVAL;
@@ -9122,7 +9120,8 @@ static long scarlett2_hwdep_read(struct snd_hwdep *hw,
 	req.offset = cpu_to_le32(*offset);
 	req.len = cpu_to_le32(count);
 
-	resp = kzalloc(count, GFP_KERNEL);
+	u8 *resp __free(kfree) =
+		kzalloc(count, GFP_KERNEL);
 	if (!resp)
 		return -ENOMEM;
 
@@ -9267,7 +9266,6 @@ static ssize_t scarlett2_devmap_read(
 	loff_t                 pos)
 {
 	struct usb_mixer_interface *mixer = entry->private_data;
-	u8           *resp_buf __free(kfree) = NULL;
 	const size_t  block_size = SCARLETT2_DEVMAP_BLOCK_SIZE;
 	size_t        copied = 0;
 
@@ -9277,7 +9275,8 @@ static ssize_t scarlett2_devmap_read(
 	if (pos + count > entry->size)
 		count = entry->size - pos;
 
-	resp_buf = kmalloc(block_size, GFP_KERNEL);
+	u8 *resp_buf __free(kfree) =
+		kmalloc(block_size, GFP_KERNEL);
 	if (!resp_buf)
 		return -ENOMEM;