Fix an integer overflow in buffer_get_data().
Fix an integer overflow in buffer_get_data().

Thanks to Orange Labs for the report.

mwgoldsmith/ssh,jahrome/libssh,substack/libssh,pouete/libssh,nviennot/libssh,kedazo/libssh,DouglasHeriot/libssh,sebadoom/libssh,mwgoldsmith/libssh,DouglasHeriot/libssh,miloj/libssh-v0.5,Distrotech/libssh,bigcat26/libssh-mod,kedazo/libssh,Distrotech/libssh,mwgoldsmith/libssh,wangshawn/libssh,taikoo/libssh,robxu9/libssh,mwgoldsmith/ssh,DouglasHeriot/libssh,miloj/libssh-v0.5,nviennot/libssh,jt1/honeypot-libssh,kedazo/libssh,mwgoldsmith/libssh,jt1/honeypot-libssh,Distrotech/libssh,mwgoldsmith/ssh,jt1/honeypot-libssh,taikoo/libssh,rofl0r/libssh,taikoo/libssh,bigcat26/libssh-mod,Distrotech/libssh,elastichosts/libssh,robxu9/libssh,jt1/honeypot-libssh,wangshawn/libssh,miloj/libssh-v0.5,pouete/libssh,rofl0r/libssh,elastichosts/libssh,nviennot/libssh,sebadoom/libssh,jahrome/libssh,pouete/libssh,DouglasHeriot/libssh,rofl0r/libssh,wangshawn/libssh,nviennot/libssh,sebadoom/libssh,mwgoldsmith/libssh,substack/libssh,elastichosts/libssh,substack/libssh,mwgoldsmith/ssh,substack/libssh,wangshawn/libssh,kedazo/libssh,bigcat26/libssh-mod,rofl0r/libssh,pouete/libssh,sebadoom/libssh,jahrome/libssh,jahrome/libssh,robxu9/libssh,taikoo/libssh,robxu9/libssh,bigcat26/libssh-mod,miloj/libssh-v0.5