[FFmpeg-devel] [PATCH 3/5] avformat/imf_cpl: xmlNodeListGetString() can return NULL

[Pierre-Anthony Lemieux]

Would this patch be an opportunity to set `cpl->content_title_utf8` to
an empty string at fill_content_title() at libavformat/imf_cpl.c if
xmlNodeListGetString() returns NULL? It could be done as a separate
patch alternatively.

LGTM otherwise.


On Sun, Jul 23, 2023 at 11:03 AM Michael Niedermayer
<michael at niedermayer.cc> wrote:
>
> Fixes: NULL pointer dereference
> Fixes: 60166/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5998301577871360
>
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavformat/imf_cpl.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/libavformat/imf_cpl.c b/libavformat/imf_cpl.c
> index fe975c2f0c..69155d786d 100644
> --- a/libavformat/imf_cpl.c
> +++ b/libavformat/imf_cpl.c
> @@ -75,6 +75,8 @@ int ff_imf_xml_read_uuid(xmlNodePtr element, AVUUID uuid)
>      int ret = 0;
>
>      xmlChar *element_text = xmlNodeListGetString(element->doc, element->xmlChildrenNode, 1);
> +    if (!element_text)
> +        return AVERROR_INVALIDDATA;
>      ret = av_uuid_urn_parse(element_text, uuid);
>      if (ret)
>          ret = AVERROR_INVALIDDATA;
> @@ -88,7 +90,7 @@ int ff_imf_xml_read_rational(xmlNodePtr element, AVRational *rational)
>      int ret = 0;
>
>      xmlChar *element_text = xmlNodeListGetString(element->doc, element->xmlChildrenNode, 1);
> -    if (sscanf(element_text, "%i %i", &rational->num, &rational->den) != 2)
> +    if (element_text == NULL || sscanf(element_text, "%i %i", &rational->num, &rational->den) != 2)
>          ret = AVERROR_INVALIDDATA;
>      xmlFree(element_text);
>
> @@ -100,7 +102,7 @@ int ff_imf_xml_read_uint32(xmlNodePtr element, uint32_t *number)
>      int ret = 0;
>
>      xmlChar *element_text = xmlNodeListGetString(element->doc, element->xmlChildrenNode, 1);
> -    if (sscanf(element_text, "%" PRIu32, number) != 1)
> +    if (element_text == NULL || sscanf(element_text, "%" PRIu32, number) != 1)
>          ret = AVERROR_INVALIDDATA;
>      xmlFree(element_text);
>
> @@ -245,6 +247,8 @@ static int fill_timecode(xmlNodePtr cpl_element, FFIMFCPL *cpl)
>          return AVERROR_INVALIDDATA;
>
>      tc_str = xmlNodeListGetString(element->doc, element->xmlChildrenNode, 1);
> +    if (!tc_str)
> +        return AVERROR_INVALIDDATA;
>      ret = parse_cpl_tc_type(tc_str, comps);
>      xmlFree(tc_str);
>      if (ret)
> --
> 2.17.1
>
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