From: Daniel Rosenberg <drosen@google.com>
Date: Mon, 2 Jul 2018 23:59:37 +0000 (-0700)
Subject: HID: debug: check length before copy_to_user()
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=717adfdaf14704fd3ec7fa2c04520c0723247eac;p=openwrt%2Fstaging%2Fblogic.git

HID: debug: check length before copy_to_user()

If our length is greater than the size of the buffer, we
overflow the buffer

Cc: stable@vger.kernel.org
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---

diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index 4f4e7a08a07b..4db8e140f709 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -1154,6 +1154,8 @@ copy_rest:
 			goto out;
 		if (list->tail > list->head) {
 			len = list->tail - list->head;
+			if (len > count)
+				len = count;
 
 			if (copy_to_user(buffer + ret, &list->hid_debug_buf[list->head], len)) {
 				ret = -EFAULT;
@@ -1163,6 +1165,8 @@ copy_rest:
 			list->head += len;
 		} else {
 			len = HID_DEBUG_BUFSIZE - list->head;
+			if (len > count)
+				len = count;
 
 			if (copy_to_user(buffer, &list->hid_debug_buf[list->head], len)) {
 				ret = -EFAULT;
@@ -1170,7 +1174,9 @@ copy_rest:
 			}
 			list->head = 0;
 			ret += len;
-			goto copy_rest;
+			count -= len;
+			if (count > 0)
+				goto copy_rest;
 		}
 
 	}