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From:   Bjorn Andersson <bjorn.andersson@linaro.org>
To:     Ohad Ben-Cohen <ohad@wizery.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>
Cc:     linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH v2 2/6] rpmsg: glink: Fix use after free in open_ack TIMEOUT case
Date:   Fri,  4 Oct 2019 15:26:58 -0700
Message-Id: <20191004222702.8632-3-bjorn.andersson@linaro.org>
In-Reply-To: <20191004222702.8632-1-bjorn.andersson@linaro.org>
References: <20191004222702.8632-1-bjorn.andersson@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Arun Kumar Neelakantam <aneela@codeaurora.org>

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>
---

Changes since v1:
- None

 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;
 }
 
-- 
2.18.0