Re: [PATCH] HID: debug: check length before copy_to_user()

On Tue, Jul 3, 2018 at 1:59 AM, Daniel Rosenberg drosen@google.com wrote:

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

Signed-off-by: Daniel Rosenberg drosen@google.com Cc: stable@vger.kernel.org

---

Looks good: Reviewed-by: Benjamin Tissoires benjamin.tissoires@redhat.com

Cheers, Benjamin

drivers/hid/hid-debug.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c index 8469b6964ff64..b48100236df89 100644 --- a/drivers/hid/hid-debug.c +++ b/drivers/hid/hid-debug.c @@ -1154,6 +1154,8 @@ static ssize_t hid_debug_events_read(struct file *file, char __user *buffer, 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 @@ static ssize_t hid_debug_events_read(struct file *file, char __user *buffer, 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 @@ static ssize_t hid_debug_events_read(struct file *file, char __user *buffer, } list->head = 0; ret += len;

•                   goto copy_rest;
  

•                   count -= len;
  

•                   if (count > 0)
  

•                           goto copy_rest;
            }
  
    }
  

-- 2.18.0.399.gad0ab374a1-goog