From 99e184a903e4f973c7358bc0c7e26fabb2237fd2 Mon Sep 17 00:00:00 2001
From: Ken Murchison <murch@andrew.cmu.edu>
Date: Fri, 25 Mar 2011 15:50:18 +0000
Subject: Fixed bug #3423 - STARTTLS plaintext command injection vulnerability

---
diff --git a/imap/imapd.c b/imap/imapd.c
index 4227d6e..f9905ae 100644
--- a/imap/imapd.c
+++ b/imap/imapd.c
@@ -1688,6 +1688,9 @@ void cmdloop()
 		if (c == '\r') c = prot_getc(imapd_in);
 		if (c != '\n') goto extraargs;
 
+		/* XXX  discard any input pipelined after STARTTLS */
+		prot_flush(imapd_in);
+
 		/* if we've already done SASL fail */
 		if (imapd_userid != NULL) {
 		    prot_printf(imapd_out, 
diff --git a/imap/lmtpengine.c b/imap/lmtpengine.c
index eff3e50..16ccc54 100644
--- a/imap/lmtpengine.c
+++ b/imap/lmtpengine.c
@@ -1562,6 +1562,9 @@ void lmtpmode(struct lmtp_func *func,
 		sasl_ssf_t ssf;
 		char *auth_id;
 
+		/* XXX  discard any input pipelined after STARTTLS */
+		prot_flush(pin);
+
 		/* SASL and openssl have different ideas
 		   about whether ssf is signed */
 		layerp = (int *) &ssf;
diff --git a/imap/mupdate.c b/imap/mupdate.c
index b6cc1cb..a4f6509 100644
--- a/imap/mupdate.c
+++ b/imap/mupdate.c
@@ -927,6 +927,9 @@ mupdate_docmd_result_t docmd(struct conn *c)
 	if (!strcmp(c->cmd.s, "Starttls")) {
 	    CHECKNEWLINE(c, ch);
 	    
+	    /* XXX  discard any input pipelined after STARTTLS */
+	    prot_flush(c->pin);
+
 	    if (!tls_enabled()) {
 		/* we don't support starttls */
 		goto badcmd;
diff --git a/imap/nntpd.c b/imap/nntpd.c
index 1c9dbb1..105fa4b 100644
--- a/imap/nntpd.c
+++ b/imap/nntpd.c
@@ -1428,6 +1428,9 @@ static void cmdloop(void)
 		if (c == '\r') c = prot_getc(nntp_in);
 		if (c != '\n') goto extraargs;
 
+		/* XXX  discard any input pipelined after STARTTLS */
+		prot_flush(nntp_in);
+
 		cmd_starttls(0);
 	    }
 	    else if (!strcmp(cmd.s, "Stat")) {
diff --git a/imap/pop3d.c b/imap/pop3d.c
index b84ca2e..7303771 100644
--- a/imap/pop3d.c
+++ b/imap/pop3d.c
@@ -930,6 +930,9 @@ static void cmdloop(void)
 		if (arg) {
 		    prot_printf(popd_out, "-ERR Unexpected extra argument\r\n");
 		} else {
+		    /* XXX  discard any input pipelined after STLS */
+		    prot_flush(popd_in);
+
 		    cmd_starttls(0);
 		}
 	    }
diff --git a/imap/sync_server.c b/imap/sync_server.c
index b2f0a7b..b8b4263 100644
--- a/imap/sync_server.c
+++ b/imap/sync_server.c
@@ -904,6 +904,9 @@ static void cmdloop(void)
 		if (c == '\r') c = prot_getc(sync_in);
 		if (c != '\n') goto extraargs;
 
+		/* XXX  discard any input pipelined after STARTTLS */
+		prot_flush(sync_in);
+
 		/* if we've already done SASL fail */
 		if (sync_userid != NULL) {
 		    prot_printf(sync_out, 
diff --git a/lib/prot.c b/lib/prot.c
index 4fef8e3..c2bb1a9 100644
--- a/lib/prot.c
+++ b/lib/prot.c
@@ -728,10 +728,30 @@ int prot_fill(struct protstream *s)
 }
 
 /*
+ * If 's' is an input stream, discard any pending/buffered data.  Otherwise,
  * Write out any buffered data in the stream 's'
  */
 int prot_flush(struct protstream *s) 
 {
+    if (!s->write) {
+	int c, save_dontblock = s->dontblock;
+
+	/* Set stream to nonblocking mode */
+	if (!save_dontblock) nonblock(s->fd, (s->dontblock = 1));
+
+	/* Ingest any pending input */
+	while ((c = prot_fill(s)) != EOF);
+
+	/* Reset stream to previous blocking mode */
+	if (!save_dontblock) nonblock(s->fd, (s->dontblock = 0));
+
+	/* Discard any buffered input */
+	s->cnt = 0;
+	s->can_unget = 0;
+
+	return 0;
+    }
+
     return prot_flush_internal(s, 1);
 }
 
diff --git a/timsieved/parser.c b/timsieved/parser.c
index 49b2881..dc710c0 100644
--- a/timsieved/parser.c
+++ b/timsieved/parser.c
@@ -443,6 +443,9 @@ int parser(struct protstream *sieved_out, struct protstream *sieved_in)
       goto error;
     }
 
+    /* XXX  discard any input pipelined after STARTTLS */
+    prot_flush(sieved_in);
+
     if(referral_host)
 	goto do_referral;
 
--
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