ext4: fix NULL pointer dereference in print_daily_error_info()

Fix NULL pointer dereference in print_daily_error_info, when   
called on unmounted fs (EXT4_SB(sb) returns NULL), by removing error 
reporting timer in ext4_put_super.

Google-Bug-Id: 3017663

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 26147746c272..751997d2cefe 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -719,6 +719,7 @@ static void ext4_put_super(struct super_block *sb)
                         ext4_abort(sb, "Couldn't clean up the journal");
         }
 
+        del_timer(&sbi->s_err_report);
         ext4_release_system_zone(sb);
         ext4_mb_release(sb);
         ext4_ext_release(sb);