Date: Mon, 19 Jan 2004 23:31:23 +0800 From: "Xin LI" <delphij@frontfree.net> To: "Xin LI" <delphij@frontfree.net>, "Anton Alin-Adrian" <aanton@reversedhell.net>, <freebsd-hackers@freebsd.org> Subject: [REVISED] Re: qmail remote root patch Message-ID: <023e01c3dea1$4d6d8570$0401a8c0@phantasm205> References: <400BD0CE.6050609@reversedhell.net> <010e01c3de91$e6daa9a0$0401a8c0@phantasm205>
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The last patch I sent to the list is incomplete because it did not handle
the case where there's too many short DELIVERED or RECEIVED lines, which
still has potential to cause memory overwrites.
I hope this time the exploit potential is completely eliminated.
Cheers,
Xin LI
--- qmail-smtpd.c.orig Mon Jan 19 23:20:38 2004
+++ qmail-smtpd.c Mon Jan 19 23:22:36 2004
@@ -305,7 +305,7 @@
*hops = 0;
flaginheader = 1;
pos = 0; flagmaybex = flagmaybey = flagmaybez = 1;
- for (;;) {
+ for (;;((*hops) < MAXHOPS)) {
substdio_get(&ssin,&ch,1);
if (flaginheader) {
if (pos < 9) {
@@ -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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