Re: [PATCH] device core: fix dma_mask handling in platform_device_register_full

Re: [PATCH] device core: fix dma_mask handling in platform_device_register_full

[Greg KH]

On Wed, Mar 11, 2020 at 05:15:51PM +0100, Christoph Hellwig wrote:
> On Wed, Mar 11, 2020 at 05:14:23PM +0100, Greg KH wrote:
> > On Wed, Mar 11, 2020 at 05:07:10PM +0100, Christoph Hellwig wrote:
> > > Ever since the generic platform device code started allocating DMA masks
> > > itself the code to allocate and leak a private DMA mask in
> > > platform_device_register_full has been superflous.  More so the fact that
> > > it unconditionally frees the DMA mask allocation in the failure path
> > > can lead to slab corruption if the function fails later on for a device
> > > where it didn't allocate the mask.  Just remove the offending code.
> > > 
> > > Fixes: cdfee5623290 ("driver core: initialize a default DMA mask for platform device")
> > > Reported-by: Artem S. Tashkinov <aros@gmx.com>
> > > Tested-by: Artem S. Tashkinov <aros@gmx.com>
> > 
> > No s-o-b from you?  :(
> > 
> > I can take this, or Linus, you can take this now if you want to as well:
> 
> Sorry, here it is:
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Is this still needed with the patch that Linus just committed to his
tree?

thanks,

greg k-h
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Re: [PATCH] device core: fix dma_mask handling in platform_device_register_full

[Christoph Hellwig]

On Wed, Mar 11, 2020 at 06:18:02PM +0100, Greg KH wrote:
> > Sorry, here it is:
> > 
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Is this still needed with the patch that Linus just committed to his
> tree?

No.
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Re: [PATCH] device core: fix dma_mask handling in platform_device_register_full

[Linus Torvalds]

On Wed, Mar 11, 2020 at 10:18 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> Is this still needed with the patch that Linus just committed to his
> tree?

My patch is basically the same, just with the field renamed too, and
not blindly just assigning to "*pdev->dev.dma_mask" (my variant does

        pdev->platform_dma_mask = pdevinfo->dma_mask;
        pdev->dev.dma_mask = &pdev->platform_dma_mask;

instead of that incomprehensible

        *pdev->dev.dma_mask = pdevinfo->dma_mask;

which depends on that dev.dma_mask pointer having been initialized in
a random place earlier).

I had the cleanups (uncommited) in my tree, and just removed the
kfree() as per Christoph.

             Linus
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