Created attachment 46044 [details]
choeger_ssl_perl_tk_biff

(gdb) bt
#0  0x400b0f8e in __read_nocancel () from /lib/tls/libpthread.so.0
#1  0x405e5ca9 in sock_read (b=0x8502c10, out=0x85086d8 "\027\003\001", 
    outl=-512) at bss_sock.c:141
#2  0x405e3bd5 in BIO_read (b=0x8502c10, out=0x85086d8, outl=5)
    at bio_lib.c:166
#3  0x40553689 in ssl3_read_n (s=0x8502800, n=5, max=5, extend=0)
    at s3_pkt.c:196
#4  0x40554123 in ssl3_read_bytes (s=0x8502800, type=23, 
    buf=0xbff93c0c "* OK imap-dhs Cyrus IMAP4 v2.1.16 server ready\r\n", 
    len=4048, peek=0) at s3_pkt.c:264
#5  0x40551eb8 in ssl3_read_internal (s=0x8502800, buf=0xbff93c0c, len=4048, 
    peek=0) at s3_lib.c:1735
#6  0x40559ce9 in SSL_read (s=0x8502800, buf=0x5, num=5) at ssl_lib.c:846
#7  0x404f7a0c in XS_Net__SSLeay_read ()
   from /usr/lib/perl5/vendor_perl/5.8.7/i586-linux-thread-multi/auto/Net/SSLeay
/SSLeay.so
#8  0x080cf4a1 in Perl_pp_entersub ()
#9  0x080b1cb6 in Perl_runops_debug ()
#10 0x0806133d in Perl_get_cv ()
#11 0x0806749d in Perl_call_sv ()
#12 0x0810e527 in Perl_pp_sysread ()
#13 0x080b1cb6 in Perl_runops_debug ()
#14 0x08068383 in perl_run ()
#15 0x0805ff5d in main ()

I don't think this is a perl problem. Please debug it a bit more... 

Well, it worked since several years now without problems, but I'll have a deeper
look.

Okay, after some experimenting and rewrite, I've now a version that works with
old and new perl versions.

Looks like sysread behaves different when used on a SSL socket then on an
ordinary socket.