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check frame bounds for gif load

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giflib does not check this either :(
This commit is contained in:
John Cupitt 2019-08-27 14:08:12 +01:00
parent 848df69a9c
commit 32e944349d
1 changed files with 27 additions and 6 deletions
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33
libvips/foreign/gifload.c
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@ -723,6 +723,11 @@ vips_foreign_load_gif_render( VipsForeignLoadGif *gif )
{
GifFileType *file = gif->file;
if( DGifGetImageDesc( file ) == GIF_ERROR ) {
vips_foreign_load_gif_error( gif );
return( -1 );
}
/* Update the colour map for this frame.
*/
vips_foreign_load_gif_build_cmap( gif );
@ -748,7 +753,28 @@ vips_foreign_load_gif_render( VipsForeignLoadGif *gif )
VIPS_IMAGE_ADDR( gif->frame, 0, 0 ),
VIPS_IMAGE_SIZEOF_IMAGE( gif->frame ) );
if( file->Image.Interlace ) {
/* giflib does not check that the Left / Top / Width / Height for this
* Image is inside the canvas.
*
* We could clip against the canvas, but for now, just ignore out of
* bounds frames. Watch for int overflow too.
*/
if( file->Image.Left < 0 ||
file->Image.Left > VIPS_MAX_COORD ||
file->Image.Width <= 0 ||
file->Image.Width > VIPS_MAX_COORD ||
file->Image.Left + file->Image.Width > file->SWidth ||
file->Image.Top < 0 ||
file->Image.Top > VIPS_MAX_COORD ||
file->Image.Height <= 0 ||
file->Image.Height > VIPS_MAX_COORD ||
file->Image.Top + file->Image.Height > file->SHeight ) {
VIPS_DEBUG_MSG( "vips_foreign_load_gif_render: "
"out of bounds frame of %d x %d pixels at %d x %d\n",
file->Image.Width, file->Image.Height,
file->Image.Left, file->Image.Top );
}
else if( file->Image.Interlace ) {
int i;
VIPS_DEBUG_MSG( "vips_foreign_load_gif_render: "
@ -862,11 +888,6 @@ vips_foreign_load_gif_next_page( VipsForeignLoadGif *gif )
VIPS_DEBUG_MSG( "vips_foreign_load_gif_next_page: "
"IMAGE_DESC_RECORD_TYPE\n" );
if( DGifGetImageDesc( gif->file ) == GIF_ERROR ) {
vips_foreign_load_gif_error( gif );
return( -1 );
}
if( vips_foreign_load_gif_render( gif ) )
return( -1 );