releases/4.4.141/pm-hibernate-fix-oops-at-snapshot_write.patch

   1 From fc14eebfc20854a38fd9f1d93a42b1783dad4d17 Mon Sep 17 00:00:00 2001
   2 From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
   3 Date: Sat, 26 May 2018 09:59:36 +0900
   4 Subject: PM / hibernate: Fix oops at snapshot_write()
   5
   6 From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
   7
   8 commit fc14eebfc20854a38fd9f1d93a42b1783dad4d17 upstream.
   9
  10 syzbot is reporting NULL pointer dereference at snapshot_write() [1].
  11 This is because data->handle is zero-cleared by ioctl(SNAPSHOT_FREE).
  12 Fix this by checking data_of(data->handle) != NULL before using it.
  13
  14 [1] https://syzkaller.appspot.com/bug?id=828a3c71bd344a6de8b6a31233d51a72099f27fd
  15
  16 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
  17 Reported-by: syzbot <syzbot+ae590932da6e45d6564d@syzkaller.appspotmail.com>
  18 Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20
  21 ---
  22  kernel/power/user.c |    5 +++++
  23  1 file changed, 5 insertions(+)
  24
  25 --- a/kernel/power/user.c
  26 +++ b/kernel/power/user.c
  27 @@ -184,6 +184,11 @@ static ssize_t snapshot_write(struct fil
  28                 res = PAGE_SIZE - pg_offp;
  29         }
  30
  31 +       if (!data_of(data->handle)) {
  32 +               res = -EINVAL;
  33 +               goto unlock;
  34 +       }
  35 +
  36         res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
  37                         buf, count);
  38         if (res > 0)