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x86/kexec: Use up-to-dated screen_info copy to fill boot params

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kexec_file_load() currently reuses the old boot_params.screen_info,
but if drivers have change the hardware state, boot_param.screen_info
could contain invalid info.

For example, the video type might be no longer VGA, or the frame buffer
address might be changed. If the kexec kernel keeps using the old screen_info,
kexec'ed kernel may attempt to write to an invalid framebuffer
memory region.

There are two screen_info instances globally available, boot_params.screen_info
and screen_info. Later one is a copy, and is updated by drivers.

So let kexec_file_load use the updated copy.

[ mingo: Tidied up the changelog. ]

Signed-off-by: Kairui Song <kasong@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20201014092429.1415040-2-kasong@redhat.com
This commit is contained in:
Kairui Song 2020-10-14 17:24:28 +08:00 committed by Ingo Molnar
parent 081dd68c89
commit afc18069a2
1 changed files with 1 additions and 2 deletions
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3
arch/x86/kernel/kexec-bzimage64.c
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@ -200,8 +200,7 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
params->hdr.hardware_subarch = boot_params.hdr.hardware_subarch;
/* Copying screen_info will do? */
memcpy(&params->screen_info, &boot_params.screen_info,
sizeof(struct screen_info));
memcpy(&params->screen_info, &screen_info, sizeof(struct screen_info));
/* Fill in memsize later */
params->screen_info.ext_mem_k = 0;