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gifload: ensure total height of all pages is sanitised #1892

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Merged
merged 1 commit into from
Nov 21, 2020
Merged

gifload: ensure total height of all pages is sanitised #1892

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Binary file added fuzz/common_fuzzer_corpus/sharpen_fuzzer-5806172036399104
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8 changes: 7 additions & 1 deletion libvips/foreign/gifload.c
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Original file line number Diff line number Diff line change
Expand Up @@ -700,8 +700,14 @@ vips_foreign_load_gif_scan_extension( VipsForeignLoadGif *gif )
static int
vips_foreign_load_gif_set_header( VipsForeignLoadGif *gif, VipsImage *image )
{
const gint64 total_height = (gint64) gif->file->SHeight * gif->n;
if ( total_height <= 0 || total_height > VIPS_MAX_COORD ) {
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You could probably still get int overflow here. How about doing the multiplication as gint64? That would be safe.

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You need to cast one of the args to the * as well, or the mult will be done as int :(

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Thanks, I've updated this, plus added an appropriate message to the error log.

vips_error( "gifload", "%s",
_( "image size out of bounds" ) );
return( -1 );
}
vips_image_init_fields( image,
gif->file->SWidth, gif->file->SHeight * gif->n,
gif->file->SWidth, (int) total_height,
(gif->has_colour ? 3 : 1) + (gif->has_transparency ? 1 : 0),
VIPS_FORMAT_UCHAR, VIPS_CODING_NONE,
gif->has_colour ?
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