From: Kairui Song <kasong@redhat.com>

Date: Wed, 14 Oct 2020 17:24:28 +0800

Patch-mainline: v5.10-rc2

References: bsc#1175306

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

Git-commit: afc18069a2cb7ead5f86623a5f3d4ad6e21f940d

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

Acked-by: Olaf Hering <ohering@suse.de>

---

 arch/x86/kernel/kexec-bzimage64.c | 3 +--

 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c

--- a/arch/x86/kernel/kexec-bzimage64.c

+++ b/arch/x86/kernel/kexec-bzimage64.c

@@ -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;