Stefano Stabellini 36e8f60f08 xen: detect uninitialized xenbus in xenbus_init
If the xenstore page hasn't been allocated properly, reading the value
of the related hvm_param (HVM_PARAM_STORE_PFN) won't actually return
error. Instead, it will succeed and return zero. Instead of attempting
to xen_remap a bad guest physical address, detect this condition and
return early.

Note that although a guest physical address of zero for
HVM_PARAM_STORE_PFN is theoretically possible, it is not a good choice
and zero has never been validly used in that capacity.

Also recognize all bits set as an invalid value.

For 32-bit Linux, any pfn above ULONG_MAX would get truncated. Pfns
above ULONG_MAX should never be passed by the Xen tools to HVM guests
anyway, so check for this condition and return early.

Cc: stable@vger.kernel.org
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Link: https://lore.kernel.org/r/20211123210748.1910236-1-sstabellini@kernel.org
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-24 08:55:15 -06:00
2021-11-14 13:56:52 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    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.
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