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b3810c5a2c
The EFI stub on x86 no longer invokes the decompressor as a subsequent boot stage, but calls into the decompression code directly while running in the context of the EFI boot services. This means that when using the native EFI entrypoint (as opposed to the EFI handover protocol, which clears BSS explicitly), the firmware PE image loader is being relied upon to ensure that BSS is zeroed before the EFI stub is entered from the firmware. As Radek's report proves, this is a bad idea. Not all loaders do this correctly, which means some global variables that should be statically initialized to 0x0 may have junk in them. So clear BSS explicitly when entering via efi_pe_entry(). Note that zeroing BSS from C code is not generally safe, but in this case, the following assignment and dereference of a global pointer variable ensures that the memset() cannot be deferred or reordered. Cc: <stable@kernel.org> # v6.1+ Reported-by: Radek Podgorny <radek@podgorny.cz> Closes: https://lore.kernel.org/all/a99a831a-8ad5-4cb0-bff9-be637311f771@podgorny.cz Signed-off-by: Ard Biesheuvel <ardb@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.