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The memblock_discard function frees the memblock.reserved.regions array, which is good. However, if a subsequent memblock_free (or memblock_phys_free) comes in later, from for example ima_free_kexec_buffer, that will result in a use after free bug in memblock_isolate_range. When running a kernel with CONFIG_KASAN enabled, this will cause a kernel panic very early in boot. Without CONFIG_KASAN, there is a chance that memblock_isolate_range might scribble on memory that is now in use by somebody else. Avoid those issues by making sure that memblock_discard points memblock.reserved.regions back at the static buffer. If memblock_free is called after memblock memory is discarded, that will print a warning in memblock_remove_region. Signed-off-by: Rik van Riel <riel@surriel.com> Link: https://lore.kernel.org/r/20230719154137.732d8525@imladris.surriel.com Signed-off-by: Mike Rapoport (IBM) <rppt@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.