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Subject: Re: general protection fault in relay_open_buf
To:     Greg KH <gregkh@linuxfoundation.org>,
        Kees Cook <keescook@chromium.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        syzbot <syzbot+16c3a70e1e9b29346c43@syzkaller.appspotmail.com>,
        Eric Biggers <ebiggers@google.com>,
        Souptick Joarder <jrdr.linux@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        David Rientjes <rientjes@google.com>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Newsgroups: gmane.linux.kernel
References: <00000000000074cbc30580b16bc3@google.com>
 <CAGXu5j+UzHKQk81RKsk39vx5WHi_CONzP4rU2fyuH-z_YB7CKw@mail.gmail.com>
 <20190131105152.GB13686@kroah.com>
From:   Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Message-ID: <f3347711-fc72-a356-0802-4c9c3ce5eb9c@I-love.SAKURA.ne.jp>
Date:   Thu, 31 Jan 2019 20:29:37 +0900
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On 2019/01/31 19:51, Greg KH wrote:
> Can you test the patch below?

You can ask syzbot to test the patch. But

> @@ -461,7 +463,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
>  		dentry = chan->cb->create_buf_file(NULL, NULL,
>  						   S_IRUSR, buf,
>  						   &chan->is_global);
> -		if (WARN_ON(dentry))
> +		if (IS_ERR_OR_NULL(dentry))
>  			goto free_buf;

are you trying to fix a different bug together that old code was by error bailing
out when chan->cb->create_buf_file() returned a valid "struct dentry *" ?
I don't know what WARN_ON() due to a valid "struct dentry *" means...

>  	}
>  
>