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

[Steven Liu]

> 2020年4月9日 下午8:58，Andreas Rheinhardt <andreas.rheinhardt at gmail.com> 写道：
> 
> 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.
Yes, you are right, I have not reproduced by this way, I double checked this way, it really have the problem,

> (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?
I have no option for other patch, only this one, because i remember Limin Wang submit one patch about this patch and I cannot not reproduced the problem which use the same way above that time, maybe I forget something i not attention. So just asked you at this patch.
I merge that patch because:
1. I cannot reproduce the bug, so have no reason to object it.
2. The other part maybe exit if strdup failed. (Real no memory for other part.)
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Thanks

Steven Liu