undefined-behavior in dvbsub parse clut segment

undefined-behavior in dvbsub parse clut segment: a task in MiMo-V2.6-RL-oss: Agentic RL Environments (MiMo RL release). UndefinedBehaviorSanitizer: undefined-behavior in function dvbsub parse clut segment in file ffmpeg/libavcodec/dvbsubdec.c