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If a change in the MMU notifier sequence number forces user_mem_abort() to return early when attempting to handle a stage-2 fault, we return uninitialised stack to kvm_handle_guest_abort(), which could potentially result in the injection of an external abort into the guest or a spurious return to userspace. Neither or these are what we want to do. Initialise 'ret' to 0 in user_mem_abort() so that bailing due to a change in the MMU notrifier sequence number is treated as though the fault was handled. Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Marc Zyngier <maz@kernel.org> Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com> Reviewed-by: Gavin Shan <gshan@redhat.com> Cc: Gavin Shan <gshan@redhat.com> Cc: Alexandru Elisei <alexandru.elisei@arm.com> Link: https://lore.kernel.org/r/20200930102442.16142-1-will@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 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.