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video/fb/fbfill: Fix potential integer overflow

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The multiplication of 2 unsigned 32-bit integers may overflow before
promotion to unsigned 64-bit. We should ensure that the multiplication
is done with overflow detection. Additionally, use grub_sub() for
subtraction.

Fixes: CID 73640, CID 73697, CID 73702, CID 73823

Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Marco A Benatto <mbenatto@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Darren Kenny 2020-11-04 15:10:51 +00:00 committed by Daniel Kiper
parent fc5951d3b1
commit 7ce3259f67
1 changed files with 13 additions and 4 deletions
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17
grub-core/video/fb/fbfill.c
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@ -31,6 +31,7 @@
#include <grub/fbfill.h>
#include <grub/fbutil.h>
#include <grub/types.h>
#include <grub/safemath.h>
#include <grub/video.h>
/* Generic filler that works for every supported mode. */
@ -61,7 +62,9 @@ grub_video_fbfill_direct32 (struct grub_video_fbblit_info *dst,
/* Calculate the number of bytes to advance from the end of one line
to the beginning of the next line. */
rowskip = dst->mode_info->pitch - dst->mode_info->bytes_per_pixel * width;
if (grub_mul (dst->mode_info->bytes_per_pixel, width, &rowskip) ||
grub_sub (dst->mode_info->pitch, rowskip, &rowskip))
return;
/* Get the start address. */
dstptr = grub_video_fb_get_video_ptr (dst, x, y);
@ -98,7 +101,9 @@ grub_video_fbfill_direct24 (struct grub_video_fbblit_info *dst,
#endif
/* Calculate the number of bytes to advance from the end of one line
to the beginning of the next line. */
rowskip = dst->mode_info->pitch - dst->mode_info->bytes_per_pixel * width;
if (grub_mul (dst->mode_info->bytes_per_pixel, width, &rowskip) ||
grub_sub (dst->mode_info->pitch, rowskip, &rowskip))
return;
/* Get the start address. */
dstptr = grub_video_fb_get_video_ptr (dst, x, y);
@ -131,7 +136,9 @@ grub_video_fbfill_direct16 (struct grub_video_fbblit_info *dst,
/* Calculate the number of bytes to advance from the end of one line
to the beginning of the next line. */
rowskip = (dst->mode_info->pitch - dst->mode_info->bytes_per_pixel * width);
if (grub_mul (dst->mode_info->bytes_per_pixel, width, &rowskip) ||
grub_sub (dst->mode_info->pitch, rowskip, &rowskip))
return;
/* Get the start address. */
dstptr = grub_video_fb_get_video_ptr (dst, x, y);
@ -161,7 +168,9 @@ grub_video_fbfill_direct8 (struct grub_video_fbblit_info *dst,
/* Calculate the number of bytes to advance from the end of one line
to the beginning of the next line. */
rowskip = dst->mode_info->pitch - dst->mode_info->bytes_per_pixel * width;
if (grub_mul (dst->mode_info->bytes_per_pixel, width, &rowskip) ||
grub_sub (dst->mode_info->pitch, rowskip, &rowskip))
return;
/* Get the start address. */
dstptr = grub_video_fb_get_video_ptr (dst, x, y);