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b938731ed2
When allocating guest stage-2 page-table pages at EL2, pKVM can consume
pages from the host-provided kvm_hyp_memcache. As pgtable.c expects
zeroed pages, guest_s2_zalloc_page() actively implements this zeroing
with a PAGE_SIZE memset. Unfortunately, we don't check the page
alignment of the host-provided address before doing so, which could
lead to the memset overrunning the page if the host was malicious.
Fix this by simply force-aligning all kvm_hyp_memcache allocations to
page boundaries.
Fixes: 60dfe093ec ("KVM: arm64: Instantiate guest stage-2 page-tables at EL2")
Reported-by: Ben Simner <ben.simner@cl.cam.ac.uk>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20250213153615.3642515-1-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
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 reStructuredText 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.