All of lore.kernel.org
 help / color / mirror / Atom feed
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org
Subject: Re: [PATCH] omap_vout: find_vma() needs ->mmap_sem held
Date: Sat, 15 Dec 2012 20:38:29 +0000	[thread overview]
Message-ID: <20121215203828.GX4939@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20121215201237.GW4939@ZenIV.linux.org.uk>

On Sat, Dec 15, 2012 at 08:12:37PM +0000, Al Viro wrote:
> 	Walking rbtree while it's modified is a Bad Idea(tm); besides,
> the result of find_vma() can be freed just as it's getting returned
> to caller.  Fortunately, it's easy to fix - just take ->mmap_sem a bit
> earlier (and don't bother with find_vma() at all if virtp >= PAGE_OFFSET -
> in that case we don't even look at its result).

	While we are at it, what prevents VIDIOC_PREPARE_BUF calling
v4l_prepare_buf() -> (e.g) vb2_ioctl_prepare_buf() -> vb2_prepare_buf() ->
__buf_prepare() -> __qbuf_userptr() -> vb2_vmalloc_get_userptr() -> find_vma(),
AFAICS without having taken ->mmap_sem anywhere in process?  The code flow
is bloody convoluted and depends on a bunch of things done by initialization,
so I certainly might've missed something...

  reply	other threads:[~2012-12-15 20:38 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-15 20:12 [PATCH] omap_vout: find_vma() needs ->mmap_sem held Al Viro
2012-12-15 20:38 ` Al Viro [this message]
2013-01-06 13:02   ` Mauro Carvalho Chehab
2013-01-07 14:03     ` Laurent Pinchart
2013-01-07 14:06     ` Laurent Pinchart
2012-12-16 20:01 ` Paul Bolle
2012-12-16 20:04   ` Al Viro
2013-01-07 14:15     ` Laurent Pinchart

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=20121215203828.GX4939@ZenIV.linux.org.uk \
    --to=viro@zeniv.linux.org.uk \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=mchehab@infradead.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.