Fix null deref in strbuf
Fix null deref in strbuf

alvarofe/sdb,alvarofe/sdb,radare/sdb,alvarofe/sdb,alvarofe/sdb,alvarofe/sdb,alvarofe/sdb,radare/sdb,radare/sdb,radare/sdb,radare/sdb,radare/sdb,radare/sdb,alvarofe/sdb,radare/sdb,alvarofe/sdb,alvarofe/sdb,alvarofe/sdb,radare/sdb,alvarofe/sdb,radare/sdb,radare/sdb