linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Jörg Otte" <jrg.otte@gmail.com>,
	"Patrick Boettcher" <patrick.boettcher@posteo.de>,
	"Mauro Carvalho Chehab" <mchehab@s-opensource.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: [v4.9-rc4] dvb-usb/cinergyT2 NULL pointer dereference
Date: Tue, 8 Nov 2016 10:42:03 -0800	[thread overview]
Message-ID: <CA+55aFxXoc3GzAXWPZL=RB2xhmhP1acR3m2S_mdoiO97+80kDA@mail.gmail.com> (raw)
In-Reply-To: <CADDKRnD6sQLsxwObi1Bo6k69P5ceqQHw7beT6C7TqZjUsDby+w@mail.gmail.com>

On Sun, Nov 6, 2016 at 7:40 AM, Jörg Otte <jrg.otte@gmail.com> wrote:
> Since v4.9-rc4 I get following crash in dvb-usb-cinergyT2 module.

Looks like it's commit 5ef8ed0e5608f ("[media] cinergyT2-core: don't
do DMA on stack"), which movced the DMA data array from the stack to
the "private" pointer. In the process it also added serialization in
the form of "data_mutex", but and now it oopses on that mutex because
the private pointer is NULL.

It looks like the "->private" pointer is allocated in dvb_usb_adapter_init()

cinergyt2_usb_probe ->
  dvb_usb_device_init ->
    dvb_usb_init() ->
      dvb_usb_adapter_init()

but the dvb_usb_init() function calls dvb_usb_device_power_ctrl()
(which calls the "power_ctrl" function, which is
cinergyt2_power_ctrl() for that drive) *before* it initializes the
private field.

Mauro, Patrick, could dvb_usb_adapter_init() be called earlier, perhaps?

                    Linus

  reply	other threads:[~2016-11-08 18:42 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-06 15:40 [v4.9-rc4] dvb-usb/cinergyT2 NULL pointer dereference Jörg Otte
2016-11-08 18:42 ` Linus Torvalds [this message]
2016-11-08 20:22   ` Mauro Carvalho Chehab
2016-11-08 21:15     ` Benjamin Larsson
2016-11-08 21:38       ` Mauro Carvalho Chehab
2016-11-09 19:57         ` Malcolm Priestley
2016-11-09 20:25           ` Mauro Carvalho Chehab
2016-11-09 11:09     ` Jörg Otte
2016-11-09 19:07       ` Linus Torvalds
2016-11-09 20:21         ` Mauro Carvalho Chehab
2016-11-10  8:40         ` Mauro Carvalho Chehab
2016-11-10 11:15           ` Jörg Otte
2016-11-11 13:55             ` Mauro Carvalho Chehab
2016-11-11 16:43               ` Jörg Otte

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CA+55aFxXoc3GzAXWPZL=RB2xhmhP1acR3m2S_mdoiO97+80kDA@mail.gmail.com' \
    --to=torvalds@linux-foundation.org \
    --cc=jrg.otte@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=mchehab@kernel.org \
    --cc=mchehab@s-opensource.com \
    --cc=patrick.boettcher@posteo.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).