usb: dwc3: Replace sscanf with kstrtou8_from_user

Variable "ubuf " and "buf" may point to  kernel address, a malicious
user could use code logic to get kernel information. Use
kstrtou8_from_user() which take care of copying buffer, and finding
u8 value here.

Change-Id: Ibb4373bdef7e921b81255d29b8650dd31b46f3c9
Signed-off-by: Liangliang Lu <luliang@codeaurora.org>

1 files changed, 26 insertions, 10 deletions

diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index 068b03a35bd5..20ac60d6b6a8 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -978,22 +978,30 @@ void dbg_print_reg(const char *name, int reg)
 static ssize_t dwc3_store_events(struct file *file,
 			    const char __user *buf, size_t count, loff_t *ppos)
 {
-	unsigned tty;
+	int ret;
+	u8 tty;
 
 	if (buf == NULL) {
 		pr_err("[%s] EINVAL\n", __func__);
-		goto done;
+		ret = -EINVAL;
+		return ret;
 	}
 
-	if (sscanf(buf, "%u", &tty) != 1 || tty > 1) {
+	ret = kstrtou8_from_user(buf, count, 0, &tty);
+	if (ret < 0) {
+		pr_err("can't get enter value.\n");
+		return ret;
+	}
+
+	if (tty > 1) {
 		pr_err("<1|0>: enable|disable console log\n");
-		goto done;
+		ret = -EINVAL;
+		return ret;
 	}
 
 	dbg_dwc3_data.tty = tty;
 	pr_info("tty = %u", dbg_dwc3_data.tty);
 
- done:
 	return count;
 }
 
@@ -1034,21 +1042,30 @@ const struct file_operations dwc3_gadget_dbg_data_fops = {
 static ssize_t dwc3_store_int_events(struct file *file,
 			const char __user *ubuf, size_t count, loff_t *ppos)
 {
-	int clear_stats, i;
+	int i, ret;
 	unsigned long flags;
 	struct seq_file *s = file->private_data;
 	struct dwc3 *dwc = s->private;
 	struct dwc3_ep *dep;
 	struct timespec ts;
+	u8 clear_stats;
 
 	if (ubuf == NULL) {
 		pr_err("[%s] EINVAL\n", __func__);
-		goto done;
+		ret = -EINVAL;
+		return ret;
+	}
+
+	ret = kstrtou8_from_user(ubuf, count, 0, &clear_stats);
+	if (ret < 0) {
+		pr_err("can't get enter value.\n");
+		return ret;
 	}
 
-	if (sscanf(ubuf, "%u", &clear_stats) != 1 || clear_stats != 0) {
+	if (clear_stats != 0) {
 		pr_err("Wrong value. To clear stats, enter value as 0.\n");
-		goto done;
+		ret = -EINVAL;
+		return ret;
 	}
 
 	spin_lock_irqsave(&dwc->lock, flags);
@@ -1065,7 +1082,6 @@ static ssize_t dwc3_store_int_events(struct file *file,
 
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
-done:
 	return count;
 }