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Fix deadlock when using dummy channels.

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Dummy channels created by ast_dummy_channel_alloc() should be destoyed by
ast_channel_unref().  Using ast_channel_release() needlessly grabs the
channel container lock and can cause a deadlock as a result.

* Analyzed use of ast_dummy_channel_alloc() and made use
ast_channel_unref() when done with the dummy channel.  (Primary reason for
the reported deadlock.)

* Made app_dial.c:dial_exec_full() not call ast_call() holding any channel
locks.  Chan_local could not perform deadlock avoidance correctly.
(Potential deadlock exposed by this issue.  Secondary reason for the
reported deadlock since the held lock was part of the deadlock chain.)

* Fixed some uses of ast_dummy_channel_alloc() not checking the returned
channel pointer for failure.

* Fixed some potential chan=NULL pointer usage in func_odbc.c.  Protected
by testing the bogus_chan value.

* Fixed needlessly clearing a 1024 char auto array when setting the first
char to zero is enough in manager.c:action_getvar().

(closes issue ASTERISK-18613)
Reported by: Thomas Arimont
Patches:
      jira_asterisk_18613_v1.8.patch (license #5621) patch uploaded by rmudgett
Tested by: Thomas Arimont


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@337973 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Richard Mudgett
2011-09-26 19:30:39 +00:00
parent 234ee31f62
commit f2e1640435
17 changed files with 96 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
main/manager.c
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@@ -3078,7 +3078,7 @@ static int action_getvar(struct mansession *s, const struct message *m)
const char *name = astman_get_header(m, "Channel");
const char *varname = astman_get_header(m, "Variable");
char *varval;
char workspace[1024] = "";
char workspace[1024];
if (ast_strlen_zero(varname)) {
astman_send_error(s, m, "No variable specified");
@@ -3092,12 +3092,12 @@ static int action_getvar(struct mansession *s, const struct message *m)
}
}
workspace[0] = '\0';
if (varname[strlen(varname) - 1] == ')') {
if (!c) {
c = ast_dummy_channel_alloc();
if (c) {
ast_func_read(c, (char *) varname, workspace, sizeof(workspace));
c = ast_channel_release(c);
} else
ast_log(LOG_ERROR, "Unable to allocate bogus channel for variable substitution. Function results may be blank.\n");
} else {