From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Darren Kenny 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 Signed-off-by: Marco A Benatto Reviewed-by: Daniel Kiper --- 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 11816d07a..a37acd1e2 100644 --- a/grub-core/video/fb/fbfill.c +++ b/grub-core/video/fb/fbfill.c @@ -31,6 +31,7 @@ #include #include #include +#include #include /* 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);