linux_dsm_epyc7002/drivers/xen
SeongJae Park c88347ae93 xenbus/xenbus_backend: Disallow pending watch messages
commit 9996bd494794a2fe393e97e7a982388c6249aa76 upstream.

'xenbus_backend' watches 'state' of devices, which is writable by
guests.  Hence, if guests intensively updates it, dom0 will have lots of
pending events that exhausting memory of dom0.  In other words, guests
can trigger dom0 memory pressure.  This is known as XSA-349.  However,
the watch callback of it, 'frontend_changed()', reads only 'state', so
doesn't need to have the pending events.

To avoid the problem, this commit disallows pending watch messages for
'xenbus_backend' using the 'will_handle()' watch callback.

This is part of XSA-349

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-30 11:54:27 +01:00
..
events
xen-pciback xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path() 2020-12-30 11:54:26 +01:00
xenbus xenbus/xenbus_backend: Disallow pending watch messages 2020-12-30 11:54:27 +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
gntdev-common.h
gntdev-dmabuf.c
gntdev-dmabuf.h
gntdev.c
grant-table.c xen: don't use page->lru for ZONE_DEVICE memory 2020-12-09 10:31:41 +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
pvcalls-front.h
swiotlb-xen.c
sys-hypervisor.c
time.c
unpopulated-alloc.c xen: don't use page->lru for ZONE_DEVICE memory 2020-12-09 10:31:41 +01:00
xen-acpi-cpuhotplug.c
xen-acpi-memhotplug.c
xen-acpi-pad.c
xen-acpi-processor.c
xen-balloon.c
xen-front-pgdir-shbuf.c
xen-scsiback.c xen: add helpers for caching grant mapping pages 2020-12-09 10:31:37 +01:00
xen-stub.c
xlate_mmu.c