Re: Patch "Revert "[media] videobuf2-v4l2: Verify planes array in buffer dequeueing"" has been added to the 4.4-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Apr 15, 2020 at 04:45:20PM +0300, Sakari Ailus wrote:
> On Wed, Apr 15, 2020 at 03:27:42PM +0200, Greg KH wrote:
> > On Wed, Apr 15, 2020 at 04:14:12PM +0300, Sakari Ailus wrote:
> > > Hi Greg,
> > > 
> > > On Wed, Apr 15, 2020 at 12:15:54PM +0200, gregkh@linuxfoundation.org wrote:
> > > > 
> > > > This is a note to let you know that I've just added the patch titled
> > > > 
> > > >     Revert "[media] videobuf2-v4l2: Verify planes array in buffer dequeueing"
> > > > 
> > > > to the 4.4-stable tree which can be found at:
> > > >     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> > > > 
> > > > The filename of the patch is:
> > > >      revert-videobuf2-v4l2-verify-planes-array-in-buffer-dequeueing.patch
> > > > and it can be found in the queue-4.4 subdirectory.
> > > > 
> > > > If you, or anyone else, feels it should not be added to the stable tree,
> > > > please let <stable@vger.kernel.org> know about it.
> > > > 
> > > > 
> > > > From 93f0750dcdaed083d6209b01e952e98ca730db66 Mon Sep 17 00:00:00 2001
> > > > From: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> > > > Date: Wed, 11 May 2016 13:09:34 -0300
> > > > Subject: Revert "[media] videobuf2-v4l2: Verify planes array in buffer dequeueing"
> > > > 
> > > > From: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> > > > 
> > > > commit 93f0750dcdaed083d6209b01e952e98ca730db66 upstream.
> > > 
> > > This patch has been already applied to the 4.4-stable tree --- and the
> > > original has been re-applied as well, just as in upstream.
> > > 
> > > The original revert was done because another patch was missing the tree
> > > (commit 93f0750dcdaed083d6209b01e952e98ca730db66 upstream), not because
> > > there was a problem with the patch itself.
> > > 
> > > In other words, this patch must be dropped.
> > 
> > Really?
> > 
> > This is a mess.  I see the following commits in the stable 4.4 tree:
> > 
> > In the 4.4.9 release the following upstream commit was backported:
> > 	2c1f6951a8a8 ("[media] videobuf2-v4l2: Verify planes array in buffer dequeueing")
> > 
> > then in 4.4.11 it was reverted by backporting:
> > 	93f0750dcdae ("Revert "[media] videobuf2-v4l2: Verify planes array in buffer dequeueing"")
> > 
> > Then finally, in 4.4.19 this commit gets added:
> > 	83934b75c368 ("[media] videobuf2-v4l2: Verify planes array in buffer dequeueing")
> > 
> > So, is 83934b75c368 ok to backport, but 2c1f6951a8a8 was not?
> 
> Both are backports of separate patches in upstream, and should be in the
> stable trees as they are at the moment (I checked 4.4). This all happened
> back in 2016 but now this revert popped up four years later.
> 
> > 
> > Because they look identical to me...
> 
> They are the same patch that got applied twice with a revert in between.
> 
> > 
> > So, what am I missing here?
> 
> The fix was originally reverted due to an issue in the API usage in DVB,
> and then re-applied with another fix in videobuf2 core. The discussion is
> here, and all these patches ended up being applied:
> 
> <URL:https://www.spinics.net/lists/linux-media/msg99334.html>
> <URL:https://www.spinics.net/lists/linux-media/msg100428.html>
> <URL:https://www.spinics.net/lists/linux-media/msg100458.html>
> 
> Applying this revert re-introduces the original kernel memory overwriting
> bug.

Ok, thanks, I'll drop this one.  Guenter, you should update your list so
you don't try to add it again :)

thanks,

greg k-h