From: Christos Tsantilas <chtsanti@users.sourceforge.net>
Date: Fri, 11 Nov 2016 16:14:16 +0000 (+0200)
Subject: Segfault via Ftp::Client::readControlReply.
X-Git-Tag: M-staged-PR71~380
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ef143ddc67151d2f8e7b466bbf091fc837701027;p=thirdparty%2Fsquid.git

Segfault via Ftp::Client::readControlReply.

Added nil dereference checks for Ftp::Client::ctrl.conn, including:
- Ftp::Client::handlePasvReply() and handleEpsvReply() that dereference
  ctrl.conn in DBG_IMPORTANT messages.
- Many functions inside FtpClient.cc and FtpGateway.cc files.

TODO: We need to find a better way to handle nil ctrl.conn. It is only
a matter of time when we forget to add another dereference check or
discover a place we missed during this change.

Also disabled forwarding of EPRT and PORT commands to origin servers.
Squid support for those commands is broken and their forwarding may
cause segfaults (bug #4004). Active FTP is still supported, of course.

This is a Measurement Factory project
---

diff --git a/src/clients/FtpClient.cc b/src/clients/FtpClient.cc
index d7d0eb31ed..29399ee66b 100644
--- a/src/clients/FtpClient.cc
+++ b/src/clients/FtpClient.cc
@@ -442,6 +442,11 @@ Ftp::Client::handlePasvReply(Ip::Address &srvAddr)
     char *buf;
     debugs(9, 3, status());
 
+    if (!Comm::IsConnOpen(ctrl.conn)) {
+        debugs(9, 5, "The control connection to the remote end is closed");
+        return false;
+    }
+
     if (code != 227) {
         debugs(9, 2, "PASV not supported by remote end");
         return false;
@@ -473,6 +478,11 @@ Ftp::Client::handleEpsvReply(Ip::Address &remoteAddr)
     char *buf;
     debugs(9, 3, status());
 
+    if (!Comm::IsConnOpen(ctrl.conn)) {
+        debugs(9, 5, "The control connection to the remote end is closed");
+        return false;
+    }
+
     if (code != 229 && code != 522) {
         if (code == 200) {
             /* handle broken servers (RFC 2428 says OK code for EPSV MUST be 229 not 200) */
@@ -735,6 +745,11 @@ Ftp::Client::sendPassive()
 void
 Ftp::Client::connectDataChannel()
 {
+    if (!Comm::IsConnOpen(ctrl.conn)) {
+        debugs(9, 5, "The control connection to the remote end is closed");
+        return;
+    }
+
     safe_free(ctrl.last_command);
 
     safe_free(ctrl.last_reply);
diff --git a/src/clients/FtpGateway.cc b/src/clients/FtpGateway.cc
index e8a1b1343a..b843cd3d0f 100644
--- a/src/clients/FtpGateway.cc
+++ b/src/clients/FtpGateway.cc
@@ -443,6 +443,11 @@ Ftp::Gateway::loginParser(const SBuf &login, bool escaped)
 void
 Ftp::Gateway::listenForDataChannel(const Comm::ConnectionPointer &conn)
 {
+    if (!Comm::IsConnOpen(ctrl.conn)) {
+        debugs(9, 5, "The control connection to the remote end is closed");
+        return;
+    }
+
     assert(!Comm::IsConnOpen(data.conn));
 
     typedef CommCbMemFunT<Gateway, CommAcceptCbParams> AcceptDialer;
@@ -1164,7 +1169,7 @@ Ftp::Gateway::start()
 
     checkUrlpath();
     buildTitleUrl();
-    debugs(9, 5, "FD " << ctrl.conn->fd << " : host=" << request->url.host() <<
+    debugs(9, 5, "FD " << (ctrl.conn ? ctrl.conn->fd : -1) << " : host=" << request->url.host() <<
            ", path=" << request->url.path() << ", user=" << user << ", passwd=" << password);
     state = BEGIN;
     Ftp::Client::start();
@@ -1719,7 +1724,9 @@ ftpReadPasv(Ftp::Gateway * ftpState)
     if (ftpState->handlePasvReply(srvAddr))
         ftpState->connectDataChannel();
     else {
-        ftpSendEPRT(ftpState);
+        ftpFail(ftpState);
+        // Currently disabled, does not work correctly:
+        // ftpSendEPRT(ftpState);
         return;
     }
 }
@@ -1759,6 +1766,11 @@ ftpOpenListenSocket(Ftp::Gateway * ftpState, int fallback)
     }
     safe_free(ftpState->data.host);
 
+    if (!Comm::IsConnOpen(ftpState->ctrl.conn)) {
+        debugs(9, 5, "The control connection to the remote end is closed");
+        return;
+    }
+
     /*
      * Set up a listen socket on the same local address as the
      * control connection.
@@ -1853,6 +1865,10 @@ ftpReadPORT(Ftp::Gateway * ftpState)
 static void
 ftpSendEPRT(Ftp::Gateway * ftpState)
 {
+    /* check the server control channel is still available */
+    if (!ftpState || !ftpState->haveControlChannel("ftpSendEPRT"))
+        return;
+
     if (Config.Ftp.epsv_all && ftpState->flags.epsv_all_sent) {
         debugs(9, DBG_IMPORTANT, "FTP does not allow EPRT method after 'EPSV ALL' has been sent.");
         return;
@@ -1914,10 +1930,8 @@ Ftp::Gateway::ftpAcceptDataConnection(const CommAcceptCbParams &io)
 {
     debugs(9, 3, HERE);
 
-    if (EBIT_TEST(entry->flags, ENTRY_ABORTED)) {
-        abortAll("entry aborted when accepting data conn");
-        data.listenConn->close();
-        data.listenConn = NULL;
+    if (!Comm::IsConnOpen(ctrl.conn)) { /*Close handlers will cleanup*/
+        debugs(9, 5, "The control connection to the remote end is closed");
         return;
     }
 
@@ -1930,6 +1944,14 @@ Ftp::Gateway::ftpAcceptDataConnection(const CommAcceptCbParams &io)
         return;
     }
 
+    if (EBIT_TEST(entry->flags, ENTRY_ABORTED)) {
+        abortAll("entry aborted when accepting data conn");
+        data.listenConn->close();
+        data.listenConn = NULL;
+        io.conn->close();
+        return;
+    }
+
     /* data listening conn is no longer even open. abort. */
     if (!Comm::IsConnOpen(data.listenConn)) {
         data.listenConn = NULL; // ensure that it's cleared and not just closed.
@@ -2682,8 +2704,8 @@ void
 Ftp::Gateway::completeForwarding()
 {
     if (fwd == NULL || flags.completed_forwarding) {
-        debugs(9, 3, HERE << "completeForwarding avoids " <<
-               "double-complete on FD " << ctrl.conn->fd << ", Data FD " << data.conn->fd <<
+        debugs(9, 3, "avoid double-complete on FD " <<
+               (ctrl.conn ? ctrl.conn->fd : -1) << ", Data FD " << data.conn->fd <<
                ", this " << this << ", fwd " << fwd);
         return;
     }