From ac74ea01860170699fb3b6ea80c0476774c8e94f Mon Sep 17 00:00:00 2001
From: Arun Kumar Neelakantam <aneela@codeaurora.org>
Date: Fri, 4 Oct 2019 15:26:58 -0700
Subject: [PATCH] rpmsg: glink: Fix use after free in open_ack TIMEOUT case
Git-commit: ac74ea01860170699fb3b6ea80c0476774c8e94f
Patch-mainline: v5.5-rc1
References: git-fixes

Extra channel reference put when remote sending OPEN_ACK after timeout
causes use-after-free while handling next remote CLOSE command.

Remove extra reference put in timeout case to avoid use-after-free.

Fixes: b4f8e52b89f6 ("rpmsg: Introduce Qualcomm RPM glink driver")
Cc: stable@vger.kernel.org
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/rpmsg/qcom_glink_native.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index 9355ce26fd98..72ed671f5dcd 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -1103,13 +1103,12 @@ static int qcom_glink_create_remote(struct qcom_glink *glink,
 close_link:
 	/*
 	 * Send a close request to "undo" our open-ack. The close-ack will
-	 * release the last reference.
+	 * release qcom_glink_send_open_req() reference and the last reference
+	 * will be relesed after receiving remote_close or transport unregister
+	 * by calling qcom_glink_native_remove().
 	 */
 	qcom_glink_send_close_req(glink, channel);
 
-	/* Release qcom_glink_send_open_req() reference */
-	kref_put(&channel->refcount, qcom_glink_channel_release);
-
 	return ret;
 }
 
-- 
2.16.4