mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-05 13:29:17 -04:00
1583052d11
AML uses SystemMemory opregions to allow AML handlers to access MMIO registers of, e.g., GPIO controllers, or access reserved regions of memory that are owned by the firmware. Currently, we also allow AML access to memory that is owned by the kernel and mapped via the linear region, which does not seem to be supported by a valid use case, and exposes the kernel's internal state to AML methods that may be buggy and exploitable. On arm64, ACPI support requires booting in EFI mode, and so we can cross reference the requested region against the EFI memory map, rather than just do a minimal check on the first page. So let's only permit regions to be remapped by the ACPI core if - they don't appear in the EFI memory map at all (which is the case for most MMIO), or - they are covered by a single region in the EFI memory map, which is not of a type that describes memory that is given to the kernel at boot. Reported-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Link: https://lore.kernel.org/r/20200626155832.2323789-2-ardb@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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.