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Merge tag 'xsa396-5.17-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
"Several Linux PV device frontends are using the grant table interfaces
for removing access rights of the backends in ways being subject to
race conditions, resulting in potential data leaks, data corruption by
malicious backends, and denial of service triggered by malicious
backends:
- blkfront, netfront, scsifront and the gntalloc driver are testing
whether a grant reference is still in use. If this is not the case,
they assume that a following removal of the granted access will
always succeed, which is not true in case the backend has mapped
the granted page between those two operations.
As a result the backend can keep access to the memory page of the
guest no matter how the page will be used after the frontend I/O
has finished. The xenbus driver has a similar problem, as it
doesn't check the success of removing the granted access of a
shared ring buffer.
- blkfront, netfront, scsifront, usbfront, dmabuf, xenbus, 9p,
kbdfront, and pvcalls are using a functionality to delay freeing a
grant reference until it is no longer in use, but the freeing of
the related data page is not synchronized with dropping the granted
access.
As a result the backend can keep access to the memory page even
after it has been freed and then re-used for a different purpose.
- netfront will fail a BUG_ON() assertion if it fails to revoke
access in the rx path.
This will result in a Denial of Service (DoS) situation of the
guest which can be triggered by the backend"
* tag 'xsa396-5.17-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/netfront: react properly to failing gnttab_end_foreign_access_ref()
xen/gnttab: fix gnttab_end_foreign_access() without page specified
xen/pvcalls: use alloc/free_pages_exact()
xen/9p: use alloc/free_pages_exact()
xen/usb: don't use gnttab_end_foreign_access() in xenhcd_gnttab_done()
xen: remove gnttab_query_foreign_access()
xen/gntalloc: don't use gnttab_query_foreign_access()
xen/scsifront: don't use gnttab_query_foreign_access() for mapped status
xen/netfront: don't use gnttab_query_foreign_access() for mapped status
xen/blkfront: don't use gnttab_query_foreign_access() for mapped status
xen/grant-table: add gnttab_try_end_foreign_access()
xen/xenbus: don't let xenbus_grant_ring() remove grants in error case
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.