James Almer:
> On 4/16/2021 4:04 PM, Michael Niedermayer wrote:
>> On Thu, Apr 15, 2021 at 06:22:10PM -0300, James Almer wrote:
>>> On 4/15/2021 5:44 PM, Michael Niedermayer wrote:
>>>> Fixes: runtime error: signed integer overflow: 65312 * 65535 cannot
>>>> be represented in type 'int'
>>>> Fixes:
>>>> 32832/clusterfuzz-testcase-minimized-ffmpeg_dem_RM_fuzzer-4817710040088576
>>>>
>>>>
>>>> Found-by: continuous fuzzing process
>>>> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
>>>> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
>>>> ---
>>>> libavformat/rmdec.c | 4 ++--
>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
>>>> index fc3bff4859..af032ed90a 100644
>>>> --- a/libavformat/rmdec.c
>>>> +++ b/libavformat/rmdec.c
>>>> @@ -269,9 +269,9 @@ static int
>>>> rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
>>>> case DEINT_ID_INT4:
>>>> if (ast->coded_framesize > ast->audio_framesize ||
>>>> sub_packet_h <= 1 ||
>>>> - ast->coded_framesize * sub_packet_h > (2 +
>>>> (sub_packet_h & 1)) * ast->audio_framesize)
>>>> + ast->coded_framesize * (uint64_t)sub_packet_h > (2
>>>> + (sub_packet_h & 1)) * ast->audio_framesize)
>>>
>>> This check seems superfluous with the one below right after it.
>>> ast->coded_framesize * sub_packet_h must be equal to 2 *
>>> ast->audio_framesize. It can be removed.
>>>
>>>> return AVERROR_INVALIDDATA;
>>>> - if (ast->coded_framesize * sub_packet_h !=
>>>> 2*ast->audio_framesize) {
>>>> + if (ast->coded_framesize * (uint64_t)sub_packet_h !=
>>>> 2*ast->audio_framesize) {
>>>> avpriv_request_sample(s, "mismatching interleaver
>>>> parameters");
>>>> return AVERROR_INVALIDDATA;
>>>> }
>>>
>>> How about something like
>>>
>>>> diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
>>>> index fc3bff4859..09880ee3fe 100644
>>>> --- a/libavformat/rmdec.c
>>>> +++ b/libavformat/rmdec.c
>>>> @@ -269,7 +269,7 @@ static int
>>>> rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
>>>> case DEINT_ID_INT4:
>>>> if (ast->coded_framesize > ast->audio_framesize ||
>>>> sub_packet_h <= 1 ||
>>>> - ast->coded_framesize * sub_packet_h > (2 +
>>>> (sub_packet_h & 1)) * ast->audio_framesize)
>>>> + ast->audio_framesize > INT_MAX / sub_packet_h)
>>>> return AVERROR_INVALIDDATA;
>>>> if (ast->coded_framesize * sub_packet_h !=
>>>> 2*ast->audio_framesize) {
>>>> avpriv_request_sample(s, "mismatching interleaver
>>>> parameters");
>>>
>>> Instead?
>>
>> The 2 if() execute different things, the 2nd requests a sample, the first
>> not. I think this suggestion would change when we request a sample
>
> Why are we returning INVALIDDATA after requesting a sample, for that
> matter? If it's considered an invalid scenario, do we really need a sample?
>
> In any case, if you don't want more files where "ast->coded_framesize *
> sub_packet_h != 2*ast->audio_framesize" would print a sample request,
> then maybe something like the following could be used instead?
>
>> diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
>> index fc3bff4859..10c1699a81 100644
>> --- a/libavformat/rmdec.c
>> +++ b/libavformat/rmdec.c
>> @@ -269,6 +269,7 @@ static int
>> rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
>> case DEINT_ID_INT4:
>> if (ast->coded_framesize > ast->audio_framesize ||
>> sub_packet_h <= 1 ||
>> + ast->audio_framesize > INT_MAX / sub_packet_h ||
>> ast->coded_framesize * sub_packet_h > (2 +
>> (sub_packet_h & 1)) * ast->audio_framesize)
>> return AVERROR_INVALIDDATA;
>> if (ast->coded_framesize * sub_packet_h !=
>> 2*ast->audio_framesize) {
>> @@ -278,12 +279,16 @@ static int
>> rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
>> break;
>> case DEINT_ID_GENR:
>> if (ast->sub_packet_size <= 0 ||
>> + ast->audio_framesize > INT_MAX / sub_packet_h ||
>> ast->sub_packet_size > ast->audio_framesize)
>> return AVERROR_INVALIDDATA;
>> if (ast->audio_framesize % ast->sub_packet_size)
>> return AVERROR_INVALIDDATA;
>> break;
>> case DEINT_ID_SIPR:
>> + if (ast->audio_framesize > INT_MAX / sub_packet_h)
sub_packet_h has not been checked for being != 0 here and in the
DEINT_ID_GENR codepath.
>> + return AVERROR_INVALIDDATA;
>> + break;
>> case DEINT_ID_INT0:
>> case DEINT_ID_VBRS:
>> case DEINT_ID_VBRF:
>> @@ -296,7 +301,6 @@ static int
>> rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
>> ast->deint_id == DEINT_ID_GENR ||
>> ast->deint_id == DEINT_ID_SIPR) {
>> if (st->codecpar->block_align <= 0 ||
>> - ast->audio_framesize * (uint64_t)sub_packet_h >
>> (unsigned)INT_MAX ||
>> ast->audio_framesize * sub_packet_h <
>> st->codecpar->block_align)
>> return AVERROR_INVALIDDATA;
>> if (av_new_packet(&ast->pkt, ast->audio_framesize *
>> sub_packet_h) < 0)
>
> Same amount of checks for all three deint ids, and no integer casting to
> prevent overflows.
Since when is a division better than casting to 64bits to perform a
multiplication?
- Andreas
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