linux-stable/drivers/xen
Juergen Gross 27dc69aa55 xen/gnttab: fix gnttab_end_foreign_access() without page specified
Commit 42baefac63 upstream.

gnttab_end_foreign_access() is used to free a grant reference and
optionally to free the associated page. In case the grant is still in
use by the other side processing is being deferred. This leads to a
problem in case no page to be freed is specified by the caller: the
caller doesn't know that the page is still mapped by the other side
and thus should not be used for other purposes.

The correct way to handle this situation is to take an additional
reference to the granted page in case handling is being deferred and
to drop that reference when the grant reference could be freed
finally.

This requires that there are no users of gnttab_end_foreign_access()
left directly repurposing the granted page after the call, as this
might result in clobbered data or information leaks via the not yet
freed grant reference.

This is part of CVE-2022-23041 / XSA-396.

Reported-by: Simon Gaiser <simon@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-11 12:22:37 +01:00
..
events xen/console: harden hvc_xen against event channel storms 2021-12-22 09:32:52 +01:00
xen-pciback
xenbus xen/xenbus: don't let xenbus_grant_ring() remove grants in error case 2022-03-11 12:22:36 +01:00
xenfs
acpi.c
arm-device.c
balloon.c
biomerge.c
cpu_hotplug.c
dbgp.c
efi.c
evtchn.c
features.c
gntalloc.c xen/gntalloc: don't use gnttab_query_foreign_access() 2022-03-11 12:22:36 +01:00
gntdev-common.h
gntdev-dmabuf.c
gntdev-dmabuf.h
gntdev.c xen/gntdev: fix unmap notification order 2022-01-27 11:05:08 +01:00
grant-table.c xen/gnttab: fix gnttab_end_foreign_access() without page specified 2022-03-11 12:22:37 +01:00
Kconfig
Makefile
manage.c
mcelog.c
mem-reservation.c
pci.c
pcpu.c
platform-pci.c
privcmd-buf.c
privcmd.c
privcmd.h
pvcalls-back.c
pvcalls-front.c xen/pvcalls: use alloc/free_pages_exact() 2022-03-11 12:22:36 +01:00
pvcalls-front.h
swiotlb-xen.c
sys-hypervisor.c
time.c
unpopulated-alloc.c
xen-acpi-pad.c
xen-acpi-processor.c
xen-balloon.c
xen-front-pgdir-shbuf.c
xen-scsiback.c
xlate_mmu.c