target/linux/generic/backport-5.15/404-v6.0-mtd-core-check-partition-before-dereference.patch

   1 From 7ec4cdb321738d44ae5d405e7b6ac73dfbf99caa Mon Sep 17 00:00:00 2001
   2 From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
   3 Date: Mon, 25 Jul 2022 22:49:25 +0900
   4 Subject: [PATCH] mtd: core: check partition before dereference
   5
   6 syzbot is reporting NULL pointer dereference at mtd_check_of_node() [1],
   7 for mtdram test device (CONFIG_MTD_MTDRAM) is not partition.
   8
   9 Link: https://syzkaller.appspot.com/bug?extid=fe013f55a2814a9e8cfd [1]
  10 Reported-by: syzbot <syzbot+fe013f55a2814a9e8cfd@syzkaller.appspotmail.com>
  11 Reported-by: kernel test robot <oliver.sang@intel.com>
  12 Fixes: ad9b10d1eaada169 ("mtd: core: introduce of support for dynamic partitions")
  13 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
  14 CC: stable@vger.kernel.org
  15 Signed-off-by: Richard Weinberger <richard@nod.at>
  16 ---
  17  drivers/mtd/mtdcore.c | 2 ++
  18  1 file changed, 2 insertions(+)
  19
  20 --- a/drivers/mtd/mtdcore.c
  21 +++ b/drivers/mtd/mtdcore.c
  22 @@ -577,6 +577,8 @@ static void mtd_check_of_node(struct mtd
  23                 return;
  24
  25         /* Check if a partitions node exist */
  26 +       if (!mtd_is_partition(mtd))
  27 +               return;
  28         parent = mtd->parent;
  29         parent_dn = dev_of_node(&parent->dev);
  30         if (!parent_dn)