queue-4.4/chardev-add-additional-check-for-minor-range-overlap.patch

   1 From 08c271e02d02ab497ace99b9f4fa7486836500a0 Mon Sep 17 00:00:00 2001
   2 From: Chengguang Xu <cgxu519@gmx.com>
   3 Date: Fri, 15 Feb 2019 20:27:11 +0800
   4 Subject: chardev: add additional check for minor range overlap
   5
   6 [ Upstream commit de36e16d1557a0b6eb328bc3516359a12ba5c25c ]
   7
   8 Current overlap checking cannot correctly handle
   9 a case which is baseminor < existing baseminor &&
  10 baseminor + minorct > existing baseminor + minorct.
  11
  12 Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
  13 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  14 Signed-off-by: Sasha Levin <sashal@kernel.org>
  15 ---
  16  fs/char_dev.c | 6 ++++++
  17  1 file changed, 6 insertions(+)
  18
  19 diff --git a/fs/char_dev.c b/fs/char_dev.c
  20 index 24b142569ca9b..d0655ca894816 100644
  21 --- a/fs/char_dev.c
  22 +++ b/fs/char_dev.c
  23 @@ -130,6 +130,12 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
  24                         ret = -EBUSY;
  25                         goto out;
  26                 }
  27 +
  28 +               if (new_min < old_min && new_max > old_max) {
  29 +                       ret = -EBUSY;
  30 +                       goto out;
  31 +               }
  32 +
  33         }
  34
  35         cd->next = *cp;
  36 --
  37 2.20.1
  38