21cb9b4143
Commit
d5cdf4cfeac9 ("efi/x86: Don't relocate the kernel unless necessary")
tries to avoid relocating the kernel in the EFI stub as far as possible.
However, when systemd-boot is used to boot a unified kernel image [1],
the image is constructed by embedding the bzImage as a .linux section in
a PE executable that contains a small stub loader from systemd that will
call the EFI stub handover entry, together with additional sections and
potentially an initrd. When this image is constructed, by for example
dracut, the initrd is placed after the bzImage without ensuring that at
least init_size bytes are available for the bzImage. If the kernel is
not relocated by the EFI stub, this could result in the compressed
kernel's startup code in head_{32,64}.S overwriting the initrd.
To prevent this, unconditionally relocate the kernel if the EFI stub was
entered via the handover entry point.
[1] https://systemd.io/BOOT_LOADER_SPECIFICATION/#type-2-efi-unified-kernel-images
Fixes: d5cdf4cfeac9 ("efi/x86: Don't relocate the kernel unless necessary")
Reported-by: Sergey Shatunov <me@prok.pw>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200406180614.429454-2-nivedita@alum.mit.edu
Link: https://lore.kernel.org/r/20200409130434.6736-5-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.