Deadlock between ast_cel_report_event and ast_do_masquerade
chan_sip calls pbx_exec on a pvt's owner channel while only the pvt lock is held. Since pbx_exec calls ast_cel_report_event which attempts to lock the channel, invalid locking order occurs. Channels should be locked before pvt's. (closes issue #15512) Reported by: lmsteffan Patches: ast_cel_deadlock_15512.diff uploaded by dvossel (license 671) git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@222981 65c4cc65-6c06-0410-ace0-fbb531ad65f3
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@ -20117,6 +20117,7 @@ static int sip_uri_cmp(const char *input1, const char *input2)
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return sip_uri_params_cmp(params1, params2);
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}
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/* \note No channel or pvt locks should be held while calling this function. */
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static int do_magic_pickup(struct ast_channel *channel, const char *extension, const char *context)
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{
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struct ast_str *str = ast_str_alloca(AST_MAX_EXTENSION + AST_MAX_CONTEXT + 2);
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@ -20794,12 +20795,17 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
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/* Do the pickup itself */
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ast_channel_unlock(c);
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*nounlock = 1;
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do_magic_pickup(c, pickup.exten, pickup.context);
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/* Now we're either masqueraded or we failed to pickup, in either case we... */
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/* since p->owner (c) is unlocked, we need to go ahead and unlock pvt for both
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* magic pickup and ast_hangup. Both of these functions will attempt to lock
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* p->owner again, which can cause a deadlock if we already hold a lock on p.
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* Locking order is, channel then pvt. Dead lock avoidance must be used if
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* called the other way around. */
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sip_pvt_unlock(p);
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do_magic_pickup(c, pickup.exten, pickup.context);
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/* Now we're either masqueraded or we failed to pickup, in either case we... */
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ast_hangup(c);
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sip_pvt_lock(p);
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sip_pvt_lock(p); /* pvt is expected to remain locked on return, so re-lock it */
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return 0;
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} else {
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