linux-kernel - Re: [RFC] printk/sysrq: Don't play with console

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190528084825.GA9676@jagdpanzerIV>
Date:   Tue, 28 May 2019 17:51:40 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Dmitry Safonov <dima@...sta.com>, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [RFC] printk/sysrq: Don't play with console_loglevel

On (05/28/19 17:02), Tetsuo Handa wrote:
> On 2019/05/28 13:22, Sergey Senozhatsky wrote:
> > On (05/28/19 12:21), Tetsuo Handa wrote:
> > [..]
> Dmitry's patch is changing only the header line (in other words, per printk() call).
> Since op_p->handler(key) is out of KERN_UNSUPPRESSED effect, the body lines might
> not be printed.

Right.

> I think that we need a way to pass KERN_UNSUPPRESSED from printk()
> calls invoked from op_p->handler(key).

Right. That's what the per-CPU context bit address.

> You are trying to omit passing KERN_UNSUPPRESSED by utilizing implicit printk
> context information. But doesn't such attempt resemble find_printk_buffer() ?

Adding KERN_UNSUPPRESSED to all printks down the op_p->handler()
line is hardly possible. At the same time I'd really prefer not
to have buffering for sysrq.

	-ss