Null pointer dereference

A Null Pointer Dereference vulnerability exits in ffjpeg d5cfd49 (2021-12-06) in bmp_load(). When the size information in metadata of the bmp is out of range, it returns without assign memory buffer to pb->pdata and did not exit the program. So the program crashes when it tries to access the pb->data, in jfif_encode() at jfif.c:763. This is due to the incomplete patch for CVE-2020-13438.