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- From 7ce3259f67ac2cd93acb0ec0080c24b3b69e66c6 Mon Sep 17 00:00:00 2001
- From: Darren Kenny <darren.kenny@oracle.com>
- Date: Wed, 4 Nov 2020 15:10:51 +0000
- Subject: [PATCH] video/fb/fbfill: Fix potential integer overflow
- 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>
- Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
- ---
- grub-core/video/fb/fbfill.c | 17 +++++++++++++----
- 1 file changed, 13 insertions(+), 4 deletions(-)
- diff --git a/grub-core/video/fb/fbfill.c b/grub-core/video/fb/fbfill.c
- index 11816d0..a37acd1 100644
- --- a/grub-core/video/fb/fbfill.c
- +++ b/grub-core/video/fb/fbfill.c
- @@ -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);
- --
- 2.14.2
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