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x86/sysfb: Fix check for bad VRAM size

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When checking whether the reported lfb_size makes sense, the height
* stride result is page-aligned before seeing whether it exceeds the
reported size.

This doesn't work if height * stride is not an exact number of pages.
For example, as reported in the kernel bugzilla below, an 800x600x32 EFI
framebuffer gets skipped because of this.

Move the PAGE_ALIGN to after the check vs size.

Reported-by: Christopher Head <chead@chead.ca>
Tested-by: Christopher Head <chead@chead.ca>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206051
Link: https://lkml.kernel.org/r/20200107230410.2291947-1-nivedita@alum.mit.edu
This commit is contained in:
Arvind Sankar 2020-01-07 18:04:10 -05:00 committed by Borislav Petkov
parent 163159aad7
commit dacc909233
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/sysfb_simplefb.c
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@ -90,11 +90,11 @@ __init int create_simplefb(const struct screen_info *si,
if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
size <<= 16;
length = mode->height * mode->stride;
length = PAGE_ALIGN(length);
if (length > size) {
printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
return -EINVAL;
}
length = PAGE_ALIGN(length);
/* setup IORESOURCE_MEM as framebuffer memory */
memset(&res, 0, sizeof(res));