Openjpeg was modified: "p_max_len -= l_nb_bytes_read;" was causing an overflow.
I'm not sure if I did something incorectly in opj_skip/opj_seek viewer side, but seems like openjpeg should have been checking remaining space in p_max_len either way.
P.S. Many thanks to Chafey and Neopallium for implementing openjpeg's partial bitstream support