chan_iax2: Prevent deadlock due to duplicate autoservice.

If a switch is invoked using chan_iax2, deadlock can result
because the PBX core is autoservicing the channel while chan_iax2
also then attempts to service it while waiting for the result
of the switch. This removes servicing of the channel to prevent
any conflicts.

ASTERISK-30064 #close

Change-Id: Ie92f206d32f9a36924af734ddde652b21106af22
This commit is contained in:
Naveen Albert 2022-05-16 13:01:48 +00:00 committed by Kevin Harwell
parent 3b7bcbb6d5
commit 82cebaa023
1 changed files with 20 additions and 28 deletions

View File

@ -14219,9 +14219,7 @@ static struct iax2_dpcache *find_cache(struct ast_channel *chan, const char *dat
{
struct iax2_dpcache *dp = NULL;
struct timeval now = ast_tvnow();
int x, com[2], timeout, old = 0, outfd, doabort, callno;
struct ast_channel *c = NULL;
struct ast_frame *f = NULL;
int x, com[2], timeout, doabort, callno;
AST_LIST_TRAVERSE_SAFE_BEGIN(&dpcache, dp, cache_list) {
if (ast_tvcmp(now, dp->expiry) > 0) {
@ -14268,8 +14266,8 @@ static struct iax2_dpcache *find_cache(struct ast_channel *chan, const char *dat
/* By here we must have a dp */
if (dp->flags & CACHE_FLAG_PENDING) {
struct timeval start;
int ms;
int res;
struct pollfd pfd;
/* Okay, here it starts to get nasty. We need a pipe now to wait
for a reply to come back so long as it's pending */
for (x = 0; x < ARRAY_LEN(dp->waiters); x++) {
@ -14290,35 +14288,31 @@ static struct iax2_dpcache *find_cache(struct ast_channel *chan, const char *dat
timeout = iaxdefaulttimeout * 1000;
/* Temporarily unlock */
AST_LIST_UNLOCK(&dpcache);
/* Defer any dtmf */
if (chan)
old = ast_channel_defer_dtmf(chan);
doabort = 0;
start = ast_tvnow();
while ((ms = ast_remaining_ms(start, timeout))) {
c = ast_waitfor_nandfds(&chan, chan ? 1 : 0, &com[0], 1, NULL, &outfd, &ms);
if (outfd > -1)
break;
if (!c)
continue;
if (!(f = ast_read(c))) {
doabort = 1;
break;
}
ast_frfree(f);
}
if (!ms) {
/* chan is in autoservice here, so do NOT service it here! */
pfd.fd = com[0];
pfd.events = POLLIN;
pfd.revents = 0;
/* Wait for pipe activity... if the channel hangs up, we'll catch it on the way out. */
res = ast_poll(&pfd, 1, timeout);
if (res < 0) {
ast_log(LOG_WARNING, "poll returned < 0: %s\n", strerror(errno));
return NULL;
} else if (!pfd.revents) {
ast_log(LOG_WARNING, "Timeout waiting for %s exten %s\n", data, exten);
}
if (ast_check_hangup(chan)) {
doabort = 1;
}
AST_LIST_LOCK(&dpcache);
dp->waiters[x] = -1;
close(com[1]);
close(com[0]);
if (doabort) {
/* Don't interpret anything, just abort. Not sure what th epoint
of undeferring dtmf on a hung up channel is but hey whatever */
if (!old && chan)
ast_channel_undefer_dtmf(chan);
/* Don't interpret anything, just abort. */
return NULL;
}
if (!(dp->flags & CACHE_FLAG_TIMEOUT)) {
@ -14341,8 +14335,6 @@ static struct iax2_dpcache *find_cache(struct ast_channel *chan, const char *dat
}
}
/* Our caller will obtain the rest */
if (!old && chan)
ast_channel_undefer_dtmf(chan);
}
return dp;
}