Re: Fwd: Segfault when downloading multiple sftp files in parallel

[Daniel Stenberg]

On Wed, 29 Jun 2016, Gou Lingfeng wrote:

My guess is that connections and session handles highly depend on one 
another (connection and disconnection need session data), but connection 
reusing needs some independence of connections.

I think you're right - and thanks a bunch for your excellent analysis and step 
by step description. It really made me understand the issue.

I think the freeing of the 'req.protop' in the disconnect function is totally 
wrong. The connection gets disconnected, it should not clear data in the easy 
handle just because of that.

See attachment for my suggested fix. I believe the free'ing should've been 
removed before already, we have just been lucky (or perhaps unlucky) that 
nobody else ran into this problem (or at least reported it) before.

--

 / daniel.haxx.seFrom 7fef4e32a1952e70b9457dbe49804e8c61cc3e58 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <dan...@haxx.se>
Date: Wed, 29 Jun 2016 23:11:43 +0200
Subject: [PATCH] conn: don't free easy handle data in handler->disconnect

Reported-by: Gou Lingfeng
Bug: https://curl.haxx.se/mail/lib-2016-06/0139.html
---
 lib/smb.c | 1 -
 lib/ssh.c | 4 ----
 2 files changed, 5 deletions(-)

diff --git a/lib/smb.c b/lib/smb.c
index 2ddbb20..56a38c2 100644
--- a/lib/smb.c
+++ b/lib/smb.c
@@ -903,11 +903,10 @@ static CURLcode smb_disconnect(struct connectdata *conn, bool dead)
   Curl_safefree(smbc->recv_buf);
 
   /* smb_done is not always called, so cleanup the request */
   if(req) {
     Curl_safefree(req->share);
-    Curl_safefree(conn->data->req.protop);
   }
 
   return CURLE_OK;
 }
 
diff --git a/lib/ssh.c b/lib/ssh.c
index e72b756..7bc3136 100644
--- a/lib/ssh.c
+++ b/lib/ssh.c
@@ -3055,12 +3055,10 @@ static CURLcode scp_disconnect(struct connectdata *conn, bool dead_connection)
 {
   CURLcode result = CURLE_OK;
   struct ssh_conn *ssh = &conn->proto.sshc;
   (void) dead_connection;
 
-  Curl_safefree(conn->data->req.protop);
-
   if(ssh->ssh_session) {
     /* only if there's a session still around to use! */
 
     state(conn, SSH_SESSION_DISCONNECT);
 
@@ -3218,12 +3216,10 @@ static CURLcode sftp_disconnect(struct connectdata *conn, bool dead_connection)
   CURLcode result = CURLE_OK;
   (void) dead_connection;
 
   DEBUGF(infof(conn->data, "SSH DISCONNECT starts now\n"));
 
-  Curl_safefree(conn->data->req.protop);
-
   if(conn->proto.sshc.ssh_session) {
     /* only if there's a session still around to use! */
     state(conn, SSH_SFTP_SHUTDOWN);
     result = ssh_block_statemach(conn, FALSE);
   }
-- 
2.8.1

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