linux-stable.git/include/xen, branch v5.15.78

xen/gnttab: fix gnttab_end_foreign_access() without page specified

2022-03-11T11:22:37+00:00

Commit 42baefac638f06314298087394b982ead9ec444b 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 
Signed-off-by: Juergen Gross 
Reviewed-by: Jan Beulich 
Signed-off-by: Greg Kroah-Hartman

xen: remove gnttab_query_foreign_access()

2022-03-11T11:22:36+00:00

Commit 1dbd11ca75fe664d3e54607547771d021f531f59 upstream.

Remove gnttab_query_foreign_access(), as it is unused and unsafe to
use.

All previous use cases assumed a grant would not be in use after
gnttab_query_foreign_access() returned 0. This information is useless
in best case, as it only refers to a situation in the past, which could
have changed already.

Signed-off-by: Juergen Gross 
Reviewed-by: Jan Beulich 
Signed-off-by: Greg Kroah-Hartman

xen/grant-table: add gnttab_try_end_foreign_access()

2022-03-11T11:22:36+00:00

Commit 6b1775f26a2da2b05a6dc8ec2b5d14e9a4701a1a upstream.

Add a new grant table function gnttab_try_end_foreign_access(), which
will remove and free a grant if it is not in use.

Its main use case is to either free a grant if it is no longer in use,
or to take some other action if it is still in use. This other action
can be an error exit, or (e.g. in the case of blkfront persistent grant
feature) some special handling.

This is CVE-2022-23036, CVE-2022-23038 / part of XSA-396.

Reported-by: Demi Marie Obenour 
Signed-off-by: Juergen Gross 
Reviewed-by: Jan Beulich 
Signed-off-by: Greg Kroah-Hartman

xen/console: harden hvc_xen against event channel storms

2021-12-22T08:32:52+00:00

commit fe415186b43df0db1f17fa3a46275fd92107fe71 upstream.

The Xen console driver is still vulnerable for an attack via excessive
number of events sent by the backend. Fix that by using a lateeoi event
channel.

For the normal domU initial console this requires the introduction of
bind_evtchn_to_irq_lateeoi() as there is no xenbus device available
at the time the event channel is bound to the irq.

As the decision whether an interrupt was spurious or not requires to
test for bytes having been read from the backend, move sending the
event into the if statement, as sending an event without having found
any bytes to be read is making no sense at all.

This is part of XSA-391

Signed-off-by: Juergen Gross 
Reviewed-by: Jan Beulich 
Signed-off-by: Greg Kroah-Hartman

xen/privcmd: drop "pages" parameter from xen_remap_pfn()

2021-10-05T06:20:27+00:00

The function doesn't use it and all of its callers say in a comment that
their respective arguments are to be non-NULL only in auto-translated
mode. Since xen_remap_domain_mfn_array() isn't supposed to be used by
non-PV, drop the parameter there as well. It was bogusly passed as non-
NULL (PRIV_VMA_LOCKED) by its only caller anyway. For
xen_remap_domain_gfn_range(), otoh, it's not clear at all why this
wouldn't want / might not need to gain auto-translated support down the
road, so the parameter is retained there despite now remaining unused
(and the only caller passing NULL); correct a respective comment as
well.

Signed-off-by: Jan Beulich 
Reviewed-by: Boris Ostrovsky 

Link: https://lore.kernel.org/r/036ad8a2-46f9-ac3d-6219-bdc93ab9e10b@suse.com
Signed-off-by: Juergen Gross

swiotlb-xen: this is PV-only on x86

2021-09-20T15:01:21+00:00

The code is unreachable for HVM or PVH, and it also makes little sense
in auto-translated environments. On Arm, with
xen_{create,destroy}_contiguous_region() both being stubs, I have a hard
time seeing what good the Xen specific variant does - the generic one
ought to be fine for all purposes there. Still Arm code explicitly
references symbols here, so the code will continue to be included there.

Instead of making PCI_XEN's "select" conditional, simply drop it -
SWIOTLB_XEN will be available unconditionally in the PV case anyway, and
is - as explained above - dead code in non-PV environments.

This in turn allows dropping the stubs for
xen_{create,destroy}_contiguous_region(), the former of which was broken
anyway - it failed to set the DMA handle output.

Signed-off-by: Jan Beulich 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Stefano Stabellini 

Link: https://lore.kernel.org/r/5947b8ae-fdc7-225c-4838-84712265fc1e@suse.com
Signed-off-by: Juergen Gross

xen: sync include/xen/interface/io/ring.h with Xen's newest version

2021-07-05T07:49:45+00:00

Sync include/xen/interface/io/ring.h with Xen's newest version in
order to get the RING_COPY_RESPONSE() and RING_RESPONSE_PROD_OVERFLOW()
macros.

Note that this will correct the wrong license info by adding the
missing original copyright notice.

Signed-off-by: Juergen Gross

xen/arm: move xen_swiotlb_detect to arm/swiotlb-xen.h

2021-05-14T13:52:05+00:00

Move xen_swiotlb_detect to a static inline function to make it available
to !CONFIG_XEN builds.

CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
Signed-off-by: Stefano Stabellini 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/20210512201823.1963-1-sstabellini@kernel.org
Signed-off-by: Juergen Gross

Merge branch 'akpm' (patches from Andrew)

2021-05-07T07:34:51+00:00

Merge yet more updates from Andrew Morton:
 "This is everything else from -mm for this merge window.

  90 patches.

  Subsystems affected by this patch series: mm (cleanups and slub),
  alpha, procfs, sysctl, misc, core-kernel, bitmap, lib, compat,
  checkpatch, epoll, isofs, nilfs2, hpfs, exit, fork, kexec, gcov,
  panic, delayacct, gdb, resource, selftests, async, initramfs, ipc,
  drivers/char, and spelling"

* emailed patches from Andrew Morton : (90 commits)
  mm: fix typos in comments
  mm: fix typos in comments
  treewide: remove editor modelines and cruft
  ipc/sem.c: spelling fix
  fs: fat: fix spelling typo of values
  kernel/sys.c: fix typo
  kernel/up.c: fix typo
  kernel/user_namespace.c: fix typos
  kernel/umh.c: fix some spelling mistakes
  include/linux/pgtable.h: few spelling fixes
  mm/slab.c: fix spelling mistake "disired" -> "desired"
  scripts/spelling.txt: add "overflw"
  scripts/spelling.txt: Add "diabled" typo
  scripts/spelling.txt: add "overlfow"
  arm: print alloc free paths for address in registers
  mm/vmalloc: remove vwrite()
  mm: remove xlate_dev_kmem_ptr()
  drivers/char: remove /dev/kmem for good
  mm: fix some typos and code style problems
  ipc/sem.c: mundane typo fixes
  ...

treewide: remove editor modelines and cruft

2021-05-07T07:26:34+00:00

The section "19) Editor modelines and other cruft" in
Documentation/process/coding-style.rst clearly says, "Do not include any
of these in source files."

I recently receive a patch to explicitly add a new one.

Let's do treewide cleanups, otherwise some people follow the existing code
and attempt to upstream their favoriate editor setups.

It is even nicer if scripts/checkpatch.pl can check it.

If we like to impose coding style in an editor-independent manner, I think
editorconfig (patch [1]) is a saner solution.

[1] https://lore.kernel.org/lkml/20200703073143.423557-1-danny@kdrag0n.dev/

Link: https://lkml.kernel.org/r/20210324054457.1477489-1-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada 
Acked-by: Geert Uytterhoeven 
Reviewed-by: Miguel Ojeda 	[auxdisplay]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds