Re: [PATCH 5.10 1/1] Reinstate some of "swiotlb: rework "fix info leak with DMA_FROM_DEVICE""

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, May 23, 2022 at 05:20:33PM +0200, Greg KH wrote:
> On Mon, May 23, 2022 at 02:40:08PM +0300, Ovidiu Panait wrote:
> > From: Linus Torvalds <torvalds@linux-foundation.org>
> > 
> > commit 901c7280ca0d5e2b4a8929fbe0bfb007ac2a6544 upstream.
> > 
> > Halil Pasic points out [1] that the full revert of that commit (revert
> > in bddac7c1e02b), and that a partial revert that only reverts the
> > problematic case, but still keeps some of the cleanups is probably
> > better.  
> > 
> > And that partial revert [2] had already been verified by Oleksandr
> > Natalenko to also fix the issue, I had just missed that in the long
> > discussion.
> > 
> > So let's reinstate the cleanups from commit aa6f8dcbab47 ("swiotlb:
> > rework "fix info leak with DMA_FROM_DEVICE""), and effectively only
> > revert the part that caused problems.
> > 
> > Link: https://lore.kernel.org/all/20220328013731.017ae3e3.pasic@linux.ibm.com/ [1]
> > Link: https://lore.kernel.org/all/20220324055732.GB12078@lst.de/ [2]
> > Link: https://lore.kernel.org/all/4386660.LvFx2qVVIh@natalenko.name/ [3]
> > Suggested-by: Halil Pasic <pasic@linux.ibm.com>
> > Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> > [OP: backport to 5.10: adjusted context]
> > Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
> > ---
> > This is part of CVE-2022-0854 patchset:
> > [1] ddbd89deb7d3 ("swiotlb: fix info leak with DMA_FROM_DEVICE")
> > [2] 901c7280ca0d ("Reinstate some of "swiotlb: rework "fix info leak with DMA_FROM_DEVICE""")
> > 
> > [1] is already present in 5.10-stable.
> > [2] is present in 5.17/5.16/5.15, but not in 5.10 and 5.4 branches;
> > 
> >  Documentation/core-api/dma-attributes.rst |  8 --------
> >  include/linux/dma-mapping.h               |  8 --------
> >  kernel/dma/swiotlb.c                      | 12 ++++++++----
> >  3 files changed, 8 insertions(+), 20 deletions(-)
> 
> This looks much different than the backport Sasha did.  I'll drop his
> and review all of this after this next round of -rc releases go out.

Nevermind, Sasha's backport looks to match this one, it was just spread
over 2 commits, so I'll leave it.

thanks,

greg k-h