[FFmpeg-devel] [PATCH]lavf/mov: Do not blindly allocate stts entries

[Carl Eugen Hoyos]

2018-01-01 16:17 GMT+01:00 Michael Niedermayer <michael at niedermayer.cc>:
> On Sun, Dec 31, 2017 at 10:35:28PM +0100, Carl Eugen Hoyos wrote:
>> 2017-12-31 22:26 GMT+01:00 Carl Eugen Hoyos <ceffmpeg at gmail.com>:
>> > 2017-12-31 22:17 GMT+01:00 Michael Niedermayer <michael at niedermayer.cc>:
>> >> On Sat, Dec 30, 2017 at 02:36:39PM +0100, Carl Eugen Hoyos wrote:
>> >>> 2017-12-29 23:37 GMT+01:00 Carl Eugen Hoyos <ceffmpeg at gmail.com>:
>> >>> > 2017-11-28 21:32 GMT+01:00 Michael Niedermayer <michael at niedermayer.cc>:
>> >>> >> On Mon, Nov 27, 2017 at 05:24:14AM +0100, Carl Eugen Hoyos wrote:
>> >>> >
>> >>> >>>      for (i = 0; i < entries && !pb->eof_reached; i++) {
>> >>> >>> -        int sample_duration;
>> >>> >>> +        int sample_duration, ret;
>> >>> >>>          unsigned int sample_count;
>> >>> >>> +        if (i > sc->stts_count) {
>> >>> >>> +            ret = av_reallocp_array(&sc->stts_data,
>> >>> >>> +                                    FFMIN(sc->stts_count * 2LL, entries),
>> >>> >>> +                                    sizeof(*sc->stts_data));
>> >>> >>
>> >>> >> this should use a variant of av_fast_realloc
>> >>> >
>> >>> > Do you prefer the new patch?
>> >>> > The old variant here looks slightly saner to me.
>> >>>
>> >>> Attached is what you possibly had in mind.
>> >>>
>> >>> Please review, Carl Eugen
>> >>
>> >>>  mov.c |   13 +++++++++++--
>> >>>  1 file changed, 11 insertions(+), 2 deletions(-)
>> >>> cc7986179fe0ddc394457e8543d9ae907b49373c  0001-lavf-mov-Use-av_fast_realloc-in-mov_read_stts.patch
>> >>> From f5fcd9ed1e5ce604c358a3787f1977277005ebb5 Mon Sep 17 00:00:00 2001
>> >>> From: Carl Eugen Hoyos <ceffmpeg at gmail.com>
>> >>> Date: Sat, 30 Dec 2017 14:34:41 +0100
>> >>> Subject: [PATCH] lavf/mov: Use av_fast_realloc() in mov_read_stts().
>> >>>
>> >>> Avoids large allocations for short files with invalid stts entry.
>> >>> Fixes bugzilla 1102.
>> >>> ---
>> >>>  libavformat/mov.c |   13 +++++++++++--
>> >>>  1 file changed, 11 insertions(+), 2 deletions(-)
>> >>>
>> >>> diff --git a/libavformat/mov.c b/libavformat/mov.c
>> >>> index 2064473..1e97652 100644
>> >>> --- a/libavformat/mov.c
>> >>> +++ b/libavformat/mov.c
>> >>> @@ -2850,13 +2850,22 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>> >>>          av_log(c->fc, AV_LOG_WARNING, "Duplicated STTS atom\n");
>> >>>      av_free(sc->stts_data);
>> >>>      sc->stts_count = 0;
>> >>> -    sc->stts_data = av_malloc_array(entries, sizeof(*sc->stts_data));
>> >>> -    if (!sc->stts_data)
>> >>> +    if (entries >= INT_MAX / sizeof(*sc->stts_data))
>> >>>          return AVERROR(ENOMEM);
>> >>
>> >> this leaves a stale pointer on error in sc->stts_data
>> >
>> > New patch attached.
>>
>> Which would not have worked as intended, new variant attached.
>>
>> Carl Eugen
>
>>  mov.c |   17 +++++++++++++----
>>  1 file changed, 13 insertions(+), 4 deletions(-)
>> c6ced82c5a98fbdf831ff4cd4809e4a02d6823c0  0001-lavf-mov-Use-av_fast_realloc-in-mov_read_stts.patch
>> From 9eaf0b56245820194e8e1bee0e3730f3c7362158 Mon Sep 17 00:00:00 2001
>> From: Carl Eugen Hoyos <ceffmpeg at gmail.com>
>> Date: Sun, 31 Dec 2017 22:30:57 +0100
>> Subject: [PATCH] lavf/mov: Use av_fast_realloc() in mov_read_stts().
>>
>> Avoids large allocations for short files with invalid stts entry.
>> Fixes bugzilla 1102.
>> ---
>>  libavformat/mov.c |   17 +++++++++++++----
>>  1 file changed, 13 insertions(+), 4 deletions(-)
>
> should be ok

Patch applied.

Thank you, Carl Eugen