On page 54 of RFC2821, a text line should be shorter than 1000 characters if
I did not misunderstood it. So I'd proposal the following patch, which
mitigate the issue by rejecting anything which contains RFC-violation.
Cheers,
Xin LI
--- qmail-smtpd.c.orig Mon Jan 19 21:08:35 2004
+++ qmail-smtpd.c Mon Jan 19 21:38:31 2004
@@ -317,7 +317,17 @@
if (pos < 2) if (ch != "\r\n"[pos]) flagmaybey = 0;
if (flagmaybey) if (pos == 1) flaginheader = 0;
}
- ++pos;
+ if((++pos) > 1000) {
+ /*
+ * RFC 2821 has explicitly defined a text line can contain
+ * 1000 characters at maximium. This is a workaround to
+ * stop copying characters there, but I am not sure about
+ * the side effect. Consider this as an attack and set hops
+ * to MAXHOPS to prevent future processing.
+ */
+ *hops = MAXHOPS;
+ break;
+ }
if (ch == '\n') { pos = 0; flagmaybex = flagmaybey = flagmaybez =
1; }
}
switch(state) {
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