It's only safe to modify the setup_data pointer on newer kernels where the EFI stub loader will ignore it. So condition setting that offset on the newer boot protocol version.
Cc: Laurent Vivier <laur...@vivier.eu> Cc: Michael S. Tsirkin <m...@redhat.com> Cc: Paolo Bonzini <pbonz...@redhat.com> Cc: Peter Maydell <peter.mayd...@linaro.org> Cc: Philippe Mathieu-Daudé <f4...@amsat.org> Cc: Richard Henderson <richard.hender...@linaro.org> Cc: Ard Biesheuvel <a...@kernel.org> Link: https://lore.kernel.org/linux-efi/20220904165321.1140894-1-ja...@zx2c4.com/ Acked-by: Gerd Hoffmann <kra...@redhat.com> Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com> --- hw/i386/x86.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/hw/i386/x86.c b/hw/i386/x86.c index 050eedc0c8..0c355c29b4 100644 --- a/hw/i386/x86.c +++ b/hw/i386/x86.c @@ -1088,8 +1088,14 @@ void x86_load_linux(X86MachineState *x86ms, qemu_guest_getrandom_nofail(setup_data->data, RNG_SEED_LENGTH); } - /* Offset 0x250 is a pointer to the first setup_data link. */ - stq_p(header + 0x250, first_setup_data); + /* + * Only modify the header if doing so won't crash EFI boot, which is the + * case only for newer boot protocols. + */ + if (protocol >= 0x210) { + /* Offset 0x250 is a pointer to the first setup_data link. */ + stq_p(header + 0x250, first_setup_data); + } /* * If we're starting an encrypted VM, it will be OVMF based, which uses the -- 2.37.3
