linux-kernel - Re: BUG: unable to handle kernel paging request in dput (2)

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Message-ID: <80e90ecd-77f5-00a3-4e91-5e9eea2aa117@I-love.SAKURA.ne.jp>
Date:   Wed, 30 Jan 2019 20:11:17 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Omar Sandoval <osandov@...com>
Cc:     syzbot <syzbot+b382ba6a802a3d242790@...kaller.appspotmail.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jens Axboe <axboe@...com>
Subject: Re: BUG: unable to handle kernel paging request in dput (2)

Hello, Omar.

syzbot is reporting a crash due to dput(-EINVAL) [1]. I think the location is

        dir = debugfs_lookup(buts->name, blk_debugfs_root);
        if (!dir)
                bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);

added by commit 6ac93117ab009d39 ("blktrace: use existing disk debugfs directory").

Currently, Greg Kroah-Hartman is posting patches:

  When calling debugfs functions, there is no need to ever check the
  return value.  The function can work or not, but the code logic should
  never do something different based on this.

Omar, what do you want to do for this case?

[1] https://syzkaller.appspot.com/bug?extid=b382ba6a802a3d242790