| Message ID | YsUydUx6FEz1ETq5@kili |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] wil6210: debugfs: fix info leak in wil_write_file_wmi() | expand |
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
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);
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(-)