[PATCH 1/2] wil6210: debugfs: fix info leak in wil_write_file_wmi()

[PATCH 1/2] wil6210: debugfs: fix info leak in wil_write_file_wmi()

[Dan Carpenter]

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@oracle.com>
---
 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 64d6c98174c8..fe84362718de 100644
--- a/drivers/net/wireless/ath/wil6210/debugfs.c
+++ b/drivers/net/wireless/ath/wil6210/debugfs.c
@@ -1012,18 +1012,12 @@ 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

[PATCH 2/2] wil6210: debugfs: replace in wil_link_stats_write() in wil_link_stats_write()

[Dan Carpenter]

This code has a check for "if (rc != len) {" so it will fail if the
simple_write_to_buffer() does not completely fill the buffer.  In
particular it will fail if "*ppos != 0". Although this code works, it is
more complicated than necessary.  Just use strndup_user() instead.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/net/wireless/ath/wil6210/debugfs.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/ath/wil6210/debugfs.c b/drivers/net/wireless/ath/wil6210/debugfs.c
index fe84362718de..591ba7f61c64 100644
--- a/drivers/net/wireless/ath/wil6210/debugfs.c
+++ b/drivers/net/wireless/ath/wil6210/debugfs.c
@@ -1937,18 +1937,15 @@ static ssize_t wil_link_stats_write(struct file *file, const char __user *buf,
 	struct wil6210_priv *wil = s->private;
 	int cid, interval, rc, i;
 	struct wil6210_vif *vif;
-	char *kbuf = kmalloc(len + 1, GFP_KERNEL);
+	char *kbuf;
 
-	if (!kbuf)
-		return -ENOMEM;
+	if (*ppos != 0)
+		return -EINVAL;
 
-	rc = simple_write_to_buffer(kbuf, len, ppos, buf, len);
-	if (rc != len) {
-		kfree(kbuf);
-		return rc >= 0 ? -EIO : rc;
-	}
+	kbuf = strndup_user(buf, len + 1);
+	if (IS_ERR(kbuf))
+		return -ENOMEM;
 
-	kbuf[len] = '\0';
 	/* specify cid (use -1 for all cids) and snapshot interval in ms */
 	rc = sscanf(kbuf, "%d %d", &cid, &interval);
 	kfree(kbuf);
-- 
2.35.1

Re: [PATCH 2/2] wil6210: debugfs: replace in wil_link_stats_write() in wil_link_stats_write()

[Dan Carpenter]

On Wed, Jul 06, 2022 at 09:57:57AM +0300, Dan Carpenter wrote:
> This code has a check for "if (rc != len) {" so it will fail if the
> simple_write_to_buffer() does not completely fill the buffer.  In
> particular it will fail if "*ppos != 0". Although this code works, it is
> more complicated than necessary.  Just use strndup_user() instead.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

NAK.  This one is buggy.  strndup_user() is too strict.  This will break
stuff.

regards,
dan carpenter