[PATCH 4.19 091/287] wifi: wil6210: debugfs: fix info leak in wil_write_file_wmi()

[Greg Kroah-Hartman]

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ Upstream commit 7a4836560a6198d245d5732e26f94898b12eb760 ]

The simple_write_to_buffer() function will succeed if even a single
byte is initialized.  However, we need to initialize the whole buffer
to prevent information leaks.  Just use memdup_user().

Fixes: ff974e408334 ("wil6210: debugfs interface to send raw WMI command")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Kalle Valo <quic_kvalo@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/Ysg14NdKAZF/hcNG@kili
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/wireless/ath/wil6210/debugfs.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/net/wireless/ath/wil6210/debugfs.c b/drivers/net/wireless/ath/wil6210/debugfs.c
index 55a809cb3105..675b2829b4c7 100644
--- a/drivers/net/wireless/ath/wil6210/debugfs.c
+++ b/drivers/net/wireless/ath/wil6210/debugfs.c
@@ -1004,18 +1004,12 @@ static ssize_t wil_write_file_wmi(struct file *file, const char __user *buf,
 	u16 cmdid;
 	int rc, rc1;
 
-	if (cmdlen < 0)
+	if (cmdlen < 0 || *ppos != 0)
 		return -EINVAL;
 
-	wmi = kmalloc(len, GFP_KERNEL);
-	if (!wmi)
-		return -ENOMEM;
-
-	rc = simple_write_to_buffer(wmi, len, ppos, buf, len);
-	if (rc < 0) {
-		kfree(wmi);
-		return rc;
-	}
+	wmi = memdup_user(buf, len);
+	if (IS_ERR(wmi))
+		return PTR_ERR(wmi);
 
 	cmd = (cmdlen > 0) ? &wmi[1] : NULL;
 	cmdid = le16_to_cpu(wmi->command_id);
-- 
2.35.1