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

[ Upstream 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
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 4d948d87f01cc081a0bae1426ae1f6c1fddaa519..a65636d60296cde2d67d2a88d1a09baca4c5765b 100644 (file)
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -211,8 +211,7 @@ 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;