From edca14c8a50e940e8d3be470d136cafa406dd596 Mon Sep 17 00:00:00 2001
From: Richard Mudgett <rmudgett@digium.com>
Date: Mon, 22 Aug 2016 12:31:24 -0500
Subject: [PATCH] res_fax.c: Fix deadlock in fax_gateway_indicate_t38().
fax_gateway_indicate_t38() calls ast_indicate_data() which cannot be
called with any channel locks already held. A deadlock can happen if the
function is operating on a local channel.
* Made fax_gateway_indicate_t38() unlock the channel before calling
ast_indicate_data() since fax_gateway_indicate_t38() is always called with
the channel locked.
* Made fax_gateway_indicate_t38() return void since nothing cared about
its return value.
ASTERISK-26203
Reported by: Etienne Lessard
ASTERISK-24822
Reported by: David Brillert
ASTERISK-22732
Reported by: Richard Mudgett
Change-Id: I701ff2d26c5fc23e0d5a48a3fd98759a9fd09407
---
res/res_fax.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/res/res_fax.c b/res/res_fax.c
index 94c512de3f..5bbc896c84 100644
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -3001,12 +3001,15 @@ static struct ast_frame *fax_gateway_detect_v21(struct fax_gateway *gateway, str
return f;
}
-static int fax_gateway_indicate_t38(struct ast_channel *chan, struct ast_channel *active, struct ast_control_t38_parameters *control_params)
+/*! \pre chan is locked on entry */
+static void fax_gateway_indicate_t38(struct ast_channel *chan, struct ast_channel *active, struct ast_control_t38_parameters *control_params)
{
if (active == chan) {
- return ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, control_params, sizeof(*control_params));
+ ast_channel_unlock(chan);
+ ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, control_params, sizeof(*control_params));
+ ast_channel_lock(chan);
} else {
- return ast_queue_control_data(chan, AST_CONTROL_T38_PARAMETERS, control_params, sizeof(*control_params));
+ ast_queue_control_data(chan, AST_CONTROL_T38_PARAMETERS, control_params, sizeof(*control_params));
}
}
--
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