Fixes: Timeout (too long -> 241ms)
Fixes: 29083/clusterfuzz-testcase-minimized-ffmpeg_dem_SWF_fuzzer-6273684478230528
The source of the magic number is
A very quick simulation of the best case compression for "compress"
below is not nice written code as i did not expect I or anyone else
would ever see it again
I would have preferred some nicer expression or course, but thats
what it seems to be asymptotically. For smaller amounts of data a
tighter bound is possible but i saw no nice way to consider that
and it seems also overkill to try to do it more fine grained for
just this
main(){
int64_t bits = 0;
int bank = 256;
int bitbank = 8;
for(unsigned i = 0; i<1024*1024*1024*4U-100000;) {
int word_size = bank-255;
i += word_size;
bits += bitbank;
if (!(bank & (bank-1)))
bitbank ++;
bank++;
if (bitbank > 16) {
printf("BEST %f \n", 8.0 * i / bits );
bank = 256;
bitbank = 8;
}
}
}
above assumes i remembered correctly how the algorithm works but the
value was close to what actual compession of zeros gave
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
The earlier code would first attempt to allocate two buffers, then
attempt to allocate an AVIOContext, using one of the new buffers I/O
buffer, then check the allocations. On success, a z_stream that is used
in the AVIOContext's read_packet callback is initialized afterwards.
There are two problems with this: In case the allocation of the I/O
buffer fails avio_alloc_context() will be given a NULL read buffer
with a size > 0. This works right now, but it is fragile. The second
problem is that the z_stream used in the read_packet callback is not
functional when avio_alloc_context() is allocated (it might be that
avio_alloc_context() might already fill the buffer in the future). This
commit fixes both of these problems by reordering the operations.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
There was almost no overlap between them: The only field used by both
was an int named samples_per_frame. Therefore this commit separates
them.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Since bae8844e the packet will always be unreferenced when a demuxer
returns an error, so that a lot of calls to av_packet_unref() in lots of
demuxers are now redundant and can be removed.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>
Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.
In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.
There are multiple important problems with this approach:
- the fields in AVCodecContext are in general one of
* stream parameters
* codec options
* codec state
However, it's not clear which ones are which. It is consequently
unclear which fields are a demuxer allowed to set or a muxer allowed to
read. This leads to erratic behaviour depending on whether decoding or
encoding is being performed or not (and whether it uses the AVStream
embedded codec context).
- various synchronization issues arising from the fact that the same
context is used by several different APIs (muxers/demuxers,
parsers, bitstream filters and encoders/decoders) simultaneously, with
there being no clear rules for who can modify what and the different
processes being typically delayed with respect to each other.
- avformat_find_stream_info() making it necessary to support opening
and closing a single codec context multiple times, thus
complicating the semantics of freeing various allocated objects in the
codec context.
Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
Fixes reading from freed data
Fixes part of Ticket3539
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Fixes use of uninitialized memory
Fixes part of msan_uninit-mem_7f055dd0ab1b_9558_videopop_guitar_300k.swf
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Fixes use of uninitialized memory
Fixes part of msan_uninit-mem_7f055dd0ab1b_9558_videopop_guitar_300k.swf
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Fixes use of uninitialized memory
Fixes msan_uninit-mem_7f90d9cce964_9558_videopop_guitar_300k.swf
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Avoids trying to read a packet with 0 or negative size.
Avoids a potential infinite loop due to seeking backwards.
Partially based on a patch by Michael Niedermayer.
We now only return in the middle of the refill in case of read error, so
inflate can be re-called if zlib needs an empty (z.avail_in=0) inflate
call for flushing.
Carl Eugen Hoyos
Michael Niedermayer
Marton Balint
Anton Khirnov
Andreas Rheinhardt
Steven Liu
Moritz Barsnick
Clément Bœsch
Hendrik Leppkes
Ronald S. Bultje
Carl Eugen Hoyos
Michael Niedermayer
James Almer
Justin Ruggles
Michael Bradshaw