[FFmpeg-devel] [PATCH] avutil/timestamp: avoid possible FPE when 0 is passed to av_ts_make_time_string2()

[Marton Balint]

On Tue, 18 Jun 2024, Rémi Denis-Courmont wrote:

>
>
> Le 17 juin 2024 22:33:01 GMT+02:00, Marton Balint <cus at passwd.hu> a écrit :
>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>> libavutil/timestamp.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavutil/timestamp.c b/libavutil/timestamp.c
>> index 2a3e3012a4..6c231a517d 100644
>> --- a/libavutil/timestamp.c
>> +++ b/libavutil/timestamp.c
>> @@ -24,7 +24,7 @@ char *av_ts_make_time_string2(char *buf, int64_t ts, AVRational tb)
>>         snprintf(buf, AV_TS_MAX_STRING_SIZE, "NOPTS");
>>     } else {
>>         double val = av_q2d(tb) * ts;
>> -        double log = floor(log10(fabs(val)));
>> +        double log = (fpclassify(val) == FP_ZERO ? -INFINITY : floor(log10(fabs(val))));
>>         int precision = (isfinite(log) && log < 0) ? -log + 5 : 6;
>
> Can the log be infinite anymore?

Yes, in case of zero value we explicitly set it to -INFINITY, but implicit 
infinity or NaN is also possible, because av_q2d can return both.

Regards,
Marton