Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <d65ee15211aa69a815bdc7cc4fc9e7c2e1bcba43.camel@perches.com>
Subject: Re: [PATCH] twist: allow converting pr_devel()/pr_debug() into
 printk(KERN_DEBUG)
From:   Joe Perches <joe@perches.com>
To:     Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-kernel@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>,
        Ondrej Mosnacek <omosnace@redhat.com>,
        Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>
Date:   Sun, 24 May 2020 10:38:02 -0700
In-Reply-To: <20200524145034.10697-1-penguin-kernel@I-love.SAKURA.ne.jp>
References: <20200524145034.10697-1-penguin-kernel@I-love.SAKURA.ne.jp>
Content-Type: text/plain; charset="ISO-8859-1"
User-Agent: Evolution 3.36.2-0ubuntu1 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sun, 2020-05-24 at 23:50 +0900, Tetsuo Handa wrote:
> syzbot found a NULL pointer dereference bug inside mptcp_recvmsg() due to
> ssock == NULL, but this bug manifested inside selinux_socket_recvmsg()
> because pr_debug() was no-op [1].
> 
>   pr_debug("fallback-read subflow=%p",
>            mptcp_subflow_ctx(ssock->sk));
>   copied = sock_recvmsg(ssock, msg, flags);

> Since console loglevel used by syzkaller will not print KERN_DEBUG
> messages to consoles, always evaluating pr_devel()/pr_debug() messages
> will not cause too much console output. Thus, let's allow fuzzers to
> always evaluate pr_devel()/pr_debug() messages.

While I think this is rather unnecessary,
what about dev_dbg/netdev_dbg/netif_dbg et al ?