[message] avoid length overflow in SetLength() (#3418)
[message] avoid length overflow in SetLength() (#3418)

Credit to OSS-Fuzz.
erja-gp/openthread,openthread/openthread,bukepo/openthread,srickardti/openthread,erja-gp/openthread,jwhui/openthread,openthread/openthread,openthread/openthread,srickardti/openthread,erja-gp/openthread,turon/openthread,lanyuwen/openthread,openthread/openthread,lanyuwen/openthread,lanyuwen/openthread,chshu/openthread,chshu/openthread,lanyuwen/openthread,chshu/openthread,lanyuwen/openthread,jwhui/openthread,jwhui/openthread,erja-gp/openthread,srickardti/openthread,abtink/openthread,erja-gp/openthread,bukepo/openthread,abtink/openthread,jwhui/openthread,abtink/openthread,turon/openthread,librasungirl/openthread,abtink/openthread,librasungirl/openthread,turon/openthread,srickardti/openthread,bukepo/openthread,erja-gp/openthread,librasungirl/openthread,turon/openthread,librasungirl/openthread,chshu/openthread,bukepo/openthread,chshu/openthread,chshu/openthread,lanyuwen/openthread