In one of case under spamcontrol-216_tgz.bin,
qmail-smtpd[XXXXXX]: segfault at 10000000b ip XXXXXXXXXX sp XXXXXXXXX error 6 in qmail-smtpd[400000+13000]

I don't know why the segfault is resolved.

diff -ur qmail-1.03-orig/qmail-smtpd.c qmail-1.03/qmail-smtpd.c
--- qmail-1.03-orig/qmail-smtpd.c	2016-03-08 10:54:42.000000000 +0900
+++ qmail-1.03/qmail-smtpd.c	2016-03-08 10:56:03.000000000 +0900
@@ -1267,7 +1267,8 @@
      {
       if (seencr == 0)
        {
-        substdio_seek(ssin,-1);
+        ssin.n += -1;
+        ssin.p -= -1;
         ch = '\r';
        }
      }