[poppler] [PATCH] Catalog::getNumPages(): validate page count

[Jason Crain]

On 2015-09-11 06:59, Even Rouault wrote:
> Hi,
> 
> here's a V2 implementing suggested changes.
> 
> Best regards,
> 
> Even

 From 0001-Catalog-getNumPages-validate-page-count.patch:
> @@ -856,6 +856,18 @@ int Catalog::getNumPages()
>        }
>      } else {
>        numPages = (int)obj.getNum();
> +      if (numPages <= 0 ) {
> +        error(errSyntaxError, -1,
> +              "Invalid page count {0:d}", numPages);
> +        numPages = 0;
> +      }
> +      else if (numPages > xref->getNumObjects()) {
> +        error(errSyntaxError, -1,
> +              "Page count ({0:d}) larger than number of objects 
> ({1:d})",
> +              numPages, xref->getNumObjects());
> +        numPages = 0;
> +      }
> +
>      }
> 
>      catDict.free();

I know I said I liked the idea of comparing the number of pages to the 
number
of objects, but on second thought, I think I could make a PDF that was 
just
many copies of the same page so it would be a completely valid PDF that 
has
more pages than objects.  I don't know of a good way to validate the 
page
count.  Even going through the page tree might be hard to do right 
without
leading to an infinite loop, in addition to being slow.