linux-kernel - Re: general protection fault in relay_open

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Message-ID: <f3347711-fc72-a356-0802-4c9c3ce5eb9c@I-love.SAKURA.ne.jp>
Date:   Thu, 31 Jan 2019 20:29:37 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Kees Cook <keescook@...omium.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        syzbot <syzbot+16c3a70e1e9b29346c43@...kaller.appspotmail.com>,
        Eric Biggers <ebiggers@...gle.com>,
        Souptick Joarder <jrdr.linux@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        David Rientjes <rientjes@...gle.com>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: general protection fault in relay_open_buf

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...

>  	}
>  
>