[FFmpeg-devel] [PATCH v2 3/7] avformat/hlsenc: Check some unchecked allocations

[Andreas Rheinhardt]

Steven Liu:
> 
> 
>> 2020年4月9日 下午5:55，Steven Liu <lq at chinaffmpeg.org> 写道：
>>
>>
>>
>>> 2020年4月9日 下午5:48，Andreas Rheinhardt <andreas.rheinhardt at gmail.com> 写道：
>>>
>>> Steven Liu:
>>>>
>>>>
>>>>> 2020年2月28日 下午5:53，Andreas Rheinhardt <andreas.rheinhardt at gmail.com> 写道：
>>>>>
>>>>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>>>>> ---
>>>>> libavformat/hlsenc.c | 13 ++++++++++++-
>>>>> 1 file changed, 12 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
>>>>> index a281c379f0..18f40ff3ed 100644
>>>>> --- a/libavformat/hlsenc.c
>>>>> +++ b/libavformat/hlsenc.c
>>>>> @@ -1610,6 +1610,8 @@ static int hls_start(AVFormatContext *s, VariantStream *vs)
>>>>>           if (c->use_localtime_mkdir) {
>>>>>               const char *dir;
>>>>>               char *fn_copy = av_strdup(oc->url);
>>>>> +                if (!fn_copy)
>>>>> +                    return AVERROR(ENOMEM);
>>>>>               dir = av_dirname(fn_copy);
>>>>>               if (ff_mkdir_p(dir) == -1 && errno != EEXIST) {
>>>>>                   av_log(oc, AV_LOG_ERROR, "Could not create directory %s with use_localtime_mkdir\n", dir);
>>>>> @@ -1770,6 +1772,8 @@ static int validate_name(int nb_vs, const char *fn)
>>>>>   }
>>>>>
>>>>>   fn_dup = av_strdup(fn);
>>>>> +    if (!fn_dup)
>>>>> +        return AVERROR(ENOMEM);
>>>>>   filename = av_basename(fn);
>>>>>   subdir_name = av_dirname(fn_dup);
>>>>>
>>>>> @@ -2139,6 +2143,8 @@ static int update_master_pl_info(AVFormatContext *s)
>>>>>   int ret = 0;
>>>>>
>>>>>   fn1 = av_strdup(s->url);
>>>>> +    if (!fn1)
>>>>> +        return AVERROR(ENOMEM);
>>>> It’s unnecessary here,
>>>> I have checked all strdup return checker in hlsenc some month ago, and double check the workflow in update_master_pl_info,
>>>> It's the safe whether you check the strdup or not.
>>>> Reference commit id: 61aa77272a25d83e5ce5c63d93c64bb9a3e15557
>>>
>>> If these strdups fail, the relevant dirnames will be wrong. While you
>>> don't get segfaults, you will not create the files at the right
>>> destinations. We should rather error out instead.
>>>
>> Maybe need reproduce the problem it let me understand the exception.
>> I need one example, command line is ok.
>>
>>
> I accept the 61aa77272a2 because i don’t know how to reproduce the exception to objection it. I have no example to objection it.
> 
Command line:
ffmpeg -i <Input file> -c copy -t 1:30 -f hls -hls_time 2
-hls_playlist_type event -master_pl_name index.m3u8
-hls_segment_filename stream_%v/data%06d.ts   -use_localtime_mkdir 1
-var_stream_map 'v:0,a:0' test/test%v/stream.m3u8
(My input file simply had H.264 video and AC-3 audio, but I don't think
that is important.)

If I run this normally, I get two subfolders in the current directory:
stream_0 and test. stream_0 contains various transport streams, test
contains index.m3u8 and a folder test0 which contains stream.m3u8.

If I simulate memory allocation failure by replacing the first strdup in
update_master_pl_info() with 'fn1 = NULL;' (instead of 'fn1 =
av_strdup(s->url);'), then the index.m3u8 file is not created in the
test subfolder, but in the current directory.

(If you believed that av_strdup() failures don't affect the outcome,
then you could have replaced all 'temp = av_strdup(str); dir =
av_dirname(temp);' with 'dir = ".";'.)

- Andreas

PS: What about the rest of this patchset?