From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>,
Ondrej Mosnacek <omosnace@redhat.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] twist: allow converting pr_devel()/pr_debug() into printk(KERN_DEBUG)
Date: Mon, 25 May 2020 18:11:57 +0900 [thread overview]
Message-ID: <20200525091157.GF755@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <20200525084218.GC5300@linux-b0ei>
On (20/05/25 10:42), Petr Mladek wrote:
> On Sun 2020-05-24 23:50:34, 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);
>
> The NULL pointer deference was found even without this patch.
> This patch would just cause that it will manifest itself on another
> place. What is the benefit, please?
Right, I don't get this patch. A NULL-deref is still a NULL pointer deref.
pr_debug() will fault reading one byte from the address and print something
like "fallback-read subflow=(efault)" to printk-safe buffer, but then
sock_recvmsg() is still going to do its thing.
-ss
next prev parent reply other threads:[~2020-05-25 9:12 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-24 14:50 Tetsuo Handa
2020-05-24 17:38 ` Joe Perches
2020-05-24 19:18 ` Ondrej Mosnacek
2020-05-25 5:03 ` Tetsuo Handa
2020-05-25 6:07 ` Joe Perches
2020-05-25 7:38 ` Dmitry Vyukov
2020-05-25 8:42 ` Petr Mladek
2020-05-25 9:11 ` Sergey Senozhatsky [this message]
2020-05-25 10:43 ` Tetsuo Handa
2020-05-27 8:37 ` Petr Mladek
2020-05-27 10:13 ` Tetsuo Handa
2020-05-27 15:55 ` Petr Mladek
2020-05-27 23:33 ` Tetsuo Handa
2020-05-28 6:56 ` [PATCH v2] twist: allow converting pr_devel()/pr_debug() into snprintf() Tetsuo Handa
2020-05-28 11:06 ` Petr Mladek
2020-05-28 15:16 ` Tetsuo Handa
2020-05-28 19:10 ` Andrew Morton
2020-05-28 19:50 ` Linus Torvalds
2020-05-28 20:01 ` Linus Torvalds
2020-05-29 0:07 ` Tetsuo Handa
2020-05-29 0:28 ` Linus Torvalds
2020-05-29 2:13 ` Tetsuo Handa
2020-05-29 2:24 ` Linus Torvalds
2020-05-29 4:47 ` Tetsuo Handa
2020-05-29 13:26 ` Tetsuo Handa
2020-06-03 11:03 ` twist: allow disabling reboot request Tetsuo Handa
2020-06-03 12:44 ` Petr Mladek
2020-06-03 13:35 ` Tetsuo Handa
2020-06-04 10:21 ` Petr Mladek
2020-06-08 7:48 ` [PATCH v2] twist: allow converting pr_devel()/pr_debug() into snprintf() Dmitry Vyukov
2020-06-08 10:30 ` Tetsuo Handa
2020-06-08 11:31 ` Andrey Konovalov
2020-05-29 8:17 ` Petr Mladek
2020-06-08 16:39 ` Geert Uytterhoeven
2020-05-28 10:59 ` [PATCH] twist: allow converting pr_devel()/pr_debug() into printk(KERN_DEBUG) Petr Mladek
2020-05-28 11:33 ` Tetsuo Handa
2020-05-28 12:14 ` Petr Mladek
2020-05-28 14:13 ` Tetsuo Handa
2020-05-28 17:08 ` Joe Perches
2020-05-29 2:04 ` Sergey Senozhatsky
2020-05-29 5:06 ` Tetsuo Handa
2020-05-27 9:59 ` kbuild test robot
2020-05-27 13:41 ` Tetsuo Handa
2020-05-27 12:37 ` kbuild test robot
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