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linux/drivers/vfio
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Alex Williamson 5d721bf222 vfio/type1: Unpin zero pages 
commit 873aefb376 upstream.

There's currently a reference count leak on the zero page.  We increment
the reference via pin_user_pages_remote(), but the page is later handled
as an invalid/reserved page, therefore it's not accounted against the
user and not unpinned by our put_pfn().

Introducing special zero page handling in put_pfn() would resolve the
leak, but without accounting of the zero page, a single user could
still create enough mappings to generate a reference count overflow.

The zero page is always resident, so for our purposes there's no reason
to keep it pinned.  Therefore, add a loop to walk pages returned from
pin_user_pages_remote() and unpin any zero pages.

Cc: stable@vger.kernel.org
Reported-by: Luboslav Pivarc <lpivarc@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/166182871735.3518559.8884121293045337358.stgit@omen
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2022-09-15 10:47:10 +02:00
..
fsl-mc vfio: Set DMA ownership for VFIO devices 2022-04-28 15:32:20 +02:00
mdev vfio/mdev: Use the driver core to create the 'remove' file 2022-04-21 07:36:56 -04:00
pci vfio: Split migration ops from main device ops 2022-08-17 15:15:48 +02:00
platform vfio: Set DMA ownership for VFIO devices 2022-04-28 15:32:20 +02:00
Kconfig vfio: Use kconfig if XX/endif blocks instead of repeating 'depends on' 2021-08-26 10:36:51 -06:00
Makefile vfio/fsl-mc: Add VFIO framework skeleton for fsl-mc devices 2020-10-07 14:17:33 -06:00
vfio.c vfio: Clear the caps->buf to NULL after free 2022-08-25 11:45:48 +02:00
vfio.h vfio: clean up the check for mediated device in vfio_iommu_type1 2021-09-30 12:46:44 -06:00
vfio_iommu_spapr_tce.c vfio/spapr_tce: reject mediated devices 2021-09-30 12:46:44 -06:00
vfio_iommu_type1.c vfio/type1: Unpin zero pages 2022-09-15 10:47:10 +02:00
vfio_spapr_eeh.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
virqfd.c vfio/virqfd: Drain events from eventfd in virqfd_wakeup() 2020-11-15 09:49:10 -05:00