On 9/4/2019 1:21 AM, Carl Eugen Hoyos wrote:
>
>
> Von meinem iPhone gesendet
>
>> Am 04.09.2019 um 01:03 schrieb James Almer <jamr...@gmail.com>:
>>
>> Speeds up the process considerably.
>>
>> Fixes ticket #8109.
>>
>> Suggested-by: nevcairiel
>> Suggested-by: cehoyos
>> Signed-off-by: James Almer <jamr...@gmail.com>
>> ---
>> libavformat/matroskadec.c | 12 ++++++++++--
>> 1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
>> index 439ee462a5..0f227eb33d 100644
>> --- a/libavformat/matroskadec.c
>> +++ b/libavformat/matroskadec.c
>> @@ -110,6 +110,7 @@ typedef const struct EbmlSyntax {
>>
>> typedef struct EbmlList {
>> int nb_elem;
>> + unsigned int alloc_elem_size;
>> void *elem;
>> } EbmlList;
>>
>> @@ -1236,8 +1237,14 @@ static int ebml_parse(MatroskaDemuxContext *matroska,
>> data = (char *) data + syntax->data_offset;
>> if (syntax->list_elem_size) {
>> EbmlList *list = data;
>> - void *newelem = av_realloc_array(list->elem, list->nb_elem + 1,
>> - syntax->list_elem_size);
>> + void *newelem;
>
>> + if ((unsigned)list->nb_elem + 1 >= UINT_MAX /
>> syntax->list_elem_size)
>> + return AVERROR(ENOMEM);
>
> I would have naively expected this to use INT_MAX.
The size parameter in av_fast_realloc() is unsigned int.
av_add_index_entry() does the exact same check.
>
> And please reconsider backporting random fixes for issues that are not
> regressions.
Despite not being a regression, the speed up from this fix on real world
files is considerable, so it's worth backporting to at least release/4.2.
>
> Carl Eugen
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