Re: [xml] [PATCH] Fix attribute decoding during XML schema validation

[Shlomi Fish]

Hi Alex,

thanks for your patch, but shouldn't a regression test be added to the code (to
protect against future breakages?)

Regards,

        Shlomi Fish

On Thu, 26 May 2016 17:43:06 -0600
Alex Henrie <alexhenri...@gmail.com> wrote:

> For https://bugzilla.gnome.org/show_bug.cgi?id=766834
> 
> vctxt->parserCtxt is always NULL in xmlSchemaSAXHandleStartElementNs,
> so this function can't call xmlStringLenDecodeEntities to decode the
> entities.
> ---
>  xmlschemas.c | 30 +++++++++++++++++++++++++-----
>  1 file changed, 25 insertions(+), 5 deletions(-)
> 
> diff --git a/xmlschemas.c b/xmlschemas.c
> index e1b3a4f..59535e5 100644
> --- a/xmlschemas.c
> +++ b/xmlschemas.c
> @@ -27391,6 +27391,7 @@ xmlSchemaSAXHandleStartElementNs(void *ctx,
>      * attributes yet.
>      */
>      if (nb_attributes != 0) {
> +     int valueLen, k, l;
>       xmlChar *value;
>  
>          for (j = 0, i = 0; i < nb_attributes; i++, j += 5) {
> @@ -27400,12 +27401,31 @@ xmlSchemaSAXHandleStartElementNs(void *ctx,
>           * libxml2 differs from normal SAX here in that it escapes all
> ampersands
>           * as &#38; instead of delivering the raw converted string.
> Changing the
>           * behavior at this point would break applications that use this
> API, so
> -         * we are forced to work around it. There is no danger of
> accidentally
> -         * decoding some entity other than &#38; in this step because
> without
> -         * unescaped ampersands there can be no other entities in the
> string.
> +         * we are forced to work around it.
>           */
> -         value = xmlStringLenDecodeEntities(vctxt->parserCtxt,
> attributes[j+3],
> -             attributes[j+4] - attributes[j+3], XML_SUBSTITUTE_REF, 0, 0,
> 0);
> +         valueLen = attributes[j+4] - attributes[j+3];
> +         value = xmlMallocAtomic(valueLen + 1);
> +         if (value == NULL) {
> +             xmlSchemaVErrMemory(vctxt,
> +                 "allocating string for decoded attribute",
> +                 NULL);
> +             goto internal_error;
> +         }
> +         for (k = 0, l = 0; k < valueLen; l++) {
> +             if (k < valueLen - 4 &&
> +                 attributes[j+3][k+0] == '&' &&
> +                 attributes[j+3][k+1] == '#' &&
> +                 attributes[j+3][k+2] == '3' &&
> +                 attributes[j+3][k+3] == '8' &&
> +                 attributes[j+3][k+4] == ';') {
> +                 value[l] = '&';
> +                 k += 5;
> +             } else {
> +                 value[l] = attributes[j+3][k];
> +                 k++;
> +             }
> +         }
> +         value[l] = '\0';
>           /*
>           * TODO: Set the node line.
>           */


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