releases/4.4.170/ext4-fix-possible-use-after-free-in-ext4_quota_enable.patch

   1 From 61157b24e60fb3cd1f85f2c76a7b1d628f970144 Mon Sep 17 00:00:00 2001
   2 From: Pan Bian <bianpan2016@163.com>
   3 Date: Mon, 3 Dec 2018 23:28:02 -0500
   4 Subject: ext4: fix possible use after free in ext4_quota_enable
   5
   6 From: Pan Bian <bianpan2016@163.com>
   7
   8 commit 61157b24e60fb3cd1f85f2c76a7b1d628f970144 upstream.
   9
  10 The function frees qf_inode via iput but then pass qf_inode to
  11 lockdep_set_quota_inode on the failure path. This may result in a
  12 use-after-free bug. The patch frees df_inode only when it is never used.
  13
  14 Fixes: daf647d2dd5 ("ext4: add lockdep annotations for i_data_sem")
  15 Cc: stable@kernel.org # 4.6
  16 Reviewed-by: Jan Kara <jack@suse.cz>
  17 Signed-off-by: Pan Bian <bianpan2016@163.com>
  18 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20
  21 ---
  22  fs/ext4/super.c |    2 +-
  23  1 file changed, 1 insertion(+), 1 deletion(-)
  24
  25 --- a/fs/ext4/super.c
  26 +++ b/fs/ext4/super.c
  27 @@ -5184,9 +5184,9 @@ static int ext4_quota_enable(struct supe
  28         qf_inode->i_flags |= S_NOQUOTA;
  29         lockdep_set_quota_inode(qf_inode, I_DATA_SEM_QUOTA);
  30         err = dquot_enable(qf_inode, type, format_id, flags);
  31 -       iput(qf_inode);
  32         if (err)
  33                 lockdep_set_quota_inode(qf_inode, I_DATA_SEM_NORMAL);
  34 +       iput(qf_inode);
  35
  36         return err;
  37  }