From: Joshua C. Colp <jcolp@sangoma.com>
Date: Fri, 19 Mar 2021 13:52:08 +0000 (-0300)
Subject: core_unreal: Fix deadlock with T.38 control frames.
X-Git-Tag: 18.3.0-rc2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=47e9ce96ea306b22c6442a8b39006844b03fef8d;p=thirdparty%2Fasterisk.git

core_unreal: Fix deadlock with T.38 control frames.

When using the ast_unreal_lock_all function no channel
locks can be held before calling it.

This change unlocks the channel that indicate was
called on before doing so and then relocks it afterwards.

ASTERISK-29035

Change-Id: Id65016201b5f9c9519a216e250f9101c629e19e9
---

diff --git a/main/core_unreal.c b/main/core_unreal.c
index 5adc90d2f7..a79fca417f 100644
--- a/main/core_unreal.c
+++ b/main/core_unreal.c
@@ -710,6 +710,7 @@ int ast_unreal_indicate(struct ast_channel *ast, int condition, const void *data
 			 * signaling and we need to be sure that the locking order is the same to prevent possible
 			 * deadlocks.
 			 */
+			ast_channel_unlock(ast);
 			ast_unreal_lock_all(p, &chan, &owner);
 
 			if (owner) {
@@ -726,12 +727,14 @@ int ast_unreal_indicate(struct ast_channel *ast, int condition, const void *data
 			}
 
 			ao2_unlock(p);
+			ast_channel_lock(ast);
 		} else if (parameters->request_response == AST_T38_TERMINATED) {
 			/*
 			 * Lock both parts of the local channel so we can restore their topologies to the original.
 			 * The topology should be on the unreal_pvt structure, with a ref that we can steal. Same
 			 * conditions as above.
 			 */
+			ast_channel_unlock(ast);
 			ast_unreal_lock_all(p, &chan, &owner);
 
 			if (owner) {
@@ -745,6 +748,7 @@ int ast_unreal_indicate(struct ast_channel *ast, int condition, const void *data
 			}
 
 			ao2_unlock(p);
+			ast_channel_lock(ast);
 		}
 
 		/*