Bug 39370 - SSL session will be removed if the client is sending close_notify
Summary: SSL session will be removed if the client is sending close_notify
Alias: None
Product: Apache httpd-2
Classification: Unclassified
Component: mod_ssl (show other bugs)
Version: 2.0-HEAD
Hardware: Other other
: P2 normal (vote)
Target Milestone: ---
Assignee: Apache HTTPD Bugs Mailing List
Keywords: MassUpdate
Depends on:
Reported: 2006-04-20 20:43 UTC by keilh
Modified: 2018-11-07 21:08 UTC (History)
0 users


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Description keilh 2006-04-20 20:43:30 UTC
If the client is closing the SSL connection correctly, i.e. sending
the close_notify alert message, the SSL session will be removed.
See the follwowing stack:

  dummy_worker(opaque = 0x16b170)
   worker_thread(thd = 0x16b170, dummy = 0x245d30)
   apr_pool_clear(pool = 0x24b428)
   run_cleanups(cref = 0x24b438)
   ssl_io_filter_cleanup(data = 0x24b9a8)
   SSL_free(s = 0x265fa0)
   ssl_clear_bad_session(s = 0x265fa0)
   SSL_CTX_remove_session(ctx = 0x23efe8, c = 0x24f560)
   remove_session_lock(ctx = 0x23efe8, c = 0x24f560, lck = 1)
   remove_session_cb(session_ctx = 0x23efe8, session = 0x24f560)

That situation is common pattern for most browser: If the server is 
sending a redirect with a large response body, the browser does not completly
read the body. 

How to reproduce:
The easiest way is a cgi script that is sending data, sleeping for
a while, sending data, etc. After seeing the first chunk in the browser,
press the stop button. 

diff with httpd/2.2.0 (the same for httpd/2.0.x)
Index: modules/ssl//ssl_engine_io.c
RCS file:
retrieving revision 1.2
diff -c -r1.2 ssl_engine_io.c
*** modules/ssl//ssl_engine_io.c        2006/02/01 17:10:55     1.2
--- modules/ssl//ssl_engine_io.c        2006/04/20 18:35:18
*** 1439,1444 ****
--- 1439,1452 ----
              status = ssl_filter_write(f, data, len);

+                       /* try to read the  close_notify of the client*/
+                       if( APR_STATUS_IS_ECONNRESET(status ) &&
+                               SSL_peek(filter_ctx->pssl, NULL,0) == 0 &&
+                               SSL_get_shutdown(filter_ctx->pssl) ==
+                       ) {
+                               SSL_set_shutdown(filter_ctx->pssl,
+                       }
              if (status != APR_SUCCESS) {

in ssl_io_filter_output will be checked that
a) the connection has been closed 
b) the client has sent the close_notify alert
  (otherwise an attacker could drop the connection, i.e.
  a truncating attack. )

(a) is just for performance)
Comment 1 William A. Rowe Jr. 2018-11-07 21:08:13 UTC
Please help us to refine our list of open and current defects; this is a mass update of old and inactive Bugzilla reports which reflect user error, already resolved defects, and still-existing defects in httpd.

As repeatedly announced, the Apache HTTP Server Project has discontinued all development and patch review of the 2.2.x series of releases. The final release 2.2.34 was published in July 2017, and no further evaluation of bug reports or security risks will be considered or published for 2.2.x releases. All reports older than 2.4.x have been updated to status RESOLVED/LATER; no further action is expected unless the report still applies to a current version of httpd.

If your report represented a question or confusion about how to use an httpd feature, an unexpected server behavior, problems building or installing httpd, or working with an external component (a third party module, browser etc.) we ask you to start by bringing your question to the User Support and Discussion mailing list, see [https://httpd.apache.org/lists.html#http-users] for details. Include a link to this Bugzilla report for completeness with your question.

If your report was clearly a defect in httpd or a feature request, we ask that you retest using a modern httpd release (2.4.33 or later) released in the past year. If it can be reproduced, please reopen this bug and change the Version field above to the httpd version you have reconfirmed with.

Your help in identifying defects or enhancements still applicable to the current httpd server software release is greatly appreciated.