[FFmpeg-devel] [PATCH 1/2] avformat/hlsenc: fix base_output_dirname is null when basename_size is 0 bug

[Marton Balint]

On Wed, 1 Nov 2017, Marton Balint wrote:

>
> On Sun, 29 Oct 2017, Liu Steven wrote:
>
>>
>>> 在 2017年10月26日，上午7:54，Steven Liu <lq at chinaffmpeg.org> 写道：
>>> 
>>> fix ticket id: #6777
>>> when use argument hls_segment_filename, the basename_size will be 0
>>> 
>>> Signed-off-by: Steven Liu <lq at chinaffmpeg.org>
>>> ---
>>> libavformat/hlsenc.c | 16 +++++++++++-----
>>> 1 file changed, 11 insertions(+), 5 deletions(-)
>>> 
>>> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
>>> index 418f153c6f..55ce800c5a 100644
>>> --- a/libavformat/hlsenc.c
>>> +++ b/libavformat/hlsenc.c
>>> @@ -1335,6 +1335,7 @@ static int hls_write_header(AVFormatContext *s)
>>>     AVDictionary *options = NULL;
>>>     int basename_size = 0;
>>>     int vtt_basename_size = 0;
>>> +    int fmp4_init_filename_len = strlen(hls->fmp4_init_filename) + 1;
>>>
>>>     if (hls->segment_type == SEGMENT_TYPE_FMP4) {
>>>         pattern = "%d.m4s";
>>> @@ -1445,7 +1446,6 @@ static int hls_write_header(AVFormatContext *s)
>>>     }
>>>
>>>     if (av_strcasecmp(hls->fmp4_init_filename, "init.mp4")) {
>>> -        int fmp4_init_filename_len = strlen(hls->fmp4_init_filename) + 1;
>>>         hls->base_output_dirname = av_malloc(fmp4_init_filename_len);
>>>         if (!hls->base_output_dirname) {
>>>             ret = AVERROR(ENOMEM);
>>> @@ -1453,19 +1453,25 @@ static int hls_write_header(AVFormatContext *s)
>>>         }
>>>         av_strlcpy(hls->base_output_dirname, hls->fmp4_init_filename, 
> fmp4_init_filename_len);
>>>     } else {
>>> -        hls->base_output_dirname = av_malloc(basename_size);
>>> +        if (basename_size > 0) {
>>> +            hls->base_output_dirname = av_malloc(basename_size);
>>> +        } else {
>>> +            hls->base_output_dirname = 
> av_malloc(strlen(hls->fmp4_init_filename));
>>> +        }
>>>         if (!hls->base_output_dirname) {
>>>             ret = AVERROR(ENOMEM);
>>>             goto fail;
>>>         }
>>> 
>>> -        av_strlcpy(hls->base_output_dirname, s->filename, basename_size);
>>> -        p = strrchr(hls->base_output_dirname, '/');
>>> +        if (basename_size > 0) {
>>> +            av_strlcpy(hls->base_output_dirname, s->filename, 
> basename_size);
>>> +            p = strrchr(hls->base_output_dirname, '/');
>>> +        }
>>>         if (p) {
>>>             *(p + 1) = '\0';
>>>             av_strlcat(hls->base_output_dirname, hls->fmp4_init_filename, 
> basename_size);
>>>         } else {
>>> -            av_strlcpy(hls->base_output_dirname, hls->fmp4_init_filename, 
> basename_size);
>>> +            av_strlcpy(hls->base_output_dirname, hls->fmp4_init_filename, 
> fmp4_init_filename_len);
>>>         }
>>>     }
>>> 
>>> -- 
>>> 2.11.0 (Apple Git-81)
>>> 
>>
>> Applied!
>>
>
> This breaks fate-filter-hls-append, ffmpeg crashes or infinite loops for 
> me:
>
> ==8410== Invalid write of size 1
> ==8410==    at 0x102DD63: av_strlcpy (avstring.c:89)
> ==8410==    by 0x6627D9: hls_write_header (hlsenc.c:1474)
> ==8410==    by 0x6BD7E1: write_header_internal (mux.c:466)
> ==8410==    by 0x6BF678: avformat_write_header (mux.c:519)
> ==8410==    by 0x4A74D8: check_init_output_file (ffmpeg.c:2933)
> ==8410==    by 0x4A8A55: init_output_stream.constprop.22 (ffmpeg.c:3572)
> ==8410==    by 0x4AC645: reap_filters (ffmpeg.c:1424)
> ==8410==    by 0x48F45E: transcode_step (ffmpeg.c:4540)
> ==8410==    by 0x48F45E: transcode (ffmpeg.c:4584)
> ==8410==    by 0x48F45E: main (ffmpeg.c:4790)
> ==8410==  Address 0xb3ded28 is 0 bytes after a block of size 8 alloc'd
> ==8410==    at 0x4C2B5D0: memalign (in 
> /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==8410==    by 0x4C2B6E7: posix_memalign (in 
> /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==8410==    by 0x1044809: av_malloc (mem.c:87)
> ==8410==    by 0x661DC0: hls_write_header (hlsenc.c:1459)
> ==8410==    by 0x6BD7E1: write_header_internal (mux.c:466)
> ==8410==    by 0x6BF678: avformat_write_header (mux.c:519)
> ==8410==    by 0x4A74D8: check_init_output_file (ffmpeg.c:2933)
> ==8410==    by 0x4A8A55: init_output_stream.constprop.22 (ffmpeg.c:3572)
> ==8410==    by 0x4AC645: reap_filters (ffmpeg.c:1424)
> ==8410==    by 0x48F45E: transcode_step (ffmpeg.c:4540)
> ==8410==    by 0x48F45E: transcode (ffmpeg.c:4584)
> ==8410==    by 0x48F45E: main (ffmpeg.c:4790)
> ==8410==

The above trace is for the offending commit, here is one for the current 
git master:

==8580== Invalid write of size 1
==8580==    at 0x102CD13: av_strlcpy (avstring.c:89)
==8580==    by 0x661B19: hls_write_header (hlsenc.c:1472)
==8580==    by 0x6BD751: write_header_internal (mux.c:466)
==8580==    by 0x6BF5E8: avformat_write_header (mux.c:519)
==8580==    by 0x4A5058: check_init_output_file (ffmpeg.c:2939)
==8580==    by 0x4A65D5: init_output_stream.constprop.23 (ffmpeg.c:3578)
==8580==    by 0x4AABB5: reap_filters (ffmpeg.c:1424)
==8580==    by 0x4AFFF8: transcode_step (ffmpeg.c:4546)
==8580==    by 0x4AFFF8: transcode (ffmpeg.c:4590)
==8580==    by 0x48DF41: main (ffmpeg.c:4796)
==8580==  Address 0xb3debe8 is 0 bytes after a block of size 8 alloc'd
==8580==    at 0x4C2B5D0: memalign (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==8580==    by 0x4C2B6E7: posix_memalign (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==8580==    by 0x10436D9: av_malloc (mem.c:87)
==8580==    by 0x661100: hls_write_header (hlsenc.c:1457)
==8580==    by 0x6BD751: write_header_internal (mux.c:466)
==8580==    by 0x6BF5E8: avformat_write_header (mux.c:519)
==8580==    by 0x4A5058: check_init_output_file (ffmpeg.c:2939)
==8580==    by 0x4A65D5: init_output_stream.constprop.23 (ffmpeg.c:3578)
==8580==    by 0x4AABB5: reap_filters (ffmpeg.c:1424)
==8580==    by 0x4AFFF8: transcode_step (ffmpeg.c:4546)
==8580==    by 0x4AFFF8: transcode (ffmpeg.c:4590)
==8580==    by 0x48DF41: main (ffmpeg.c:4796)
==8580==

Regards,
Marton