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From:   Shengjiu Wang <shengjiu.wang@nxp.com>
To:     bjorn.andersson@linaro.org, mathieu.poirier@linaro.org,
        arnaud.pouliquen@foss.st.com
Cc:     linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org,
        shengjiu.wang@gmail.com
Subject: [PATCH] rpmsg: char: Avoid double destroy of default endpoint
Date:   Fri, 16 Sep 2022 14:39:26 +0800
Message-Id: <1663310366-720-1-git-send-email-shengjiu.wang@nxp.com>
Precedence: bulk

The rpmsg_dev_remove() in rpmsg_core is the place for releasing
this default endpoint.

So need to avoid destroying the default endpoint in
rpmsg_chrdev_eptdev_destroy(), this should be the same as
rpmsg_eptdev_release(). Otherwise there will be double destroy
issue that ept->refcount report warning:

refcount_t: underflow; use-after-free.

Call trace:
 refcount_warn_saturate+0xf8/0x150
 virtio_rpmsg_destroy_ept+0xd4/0xec
 rpmsg_dev_remove+0x60/0x70

Fixes: bea9b79c2d10 ("rpmsg: char: Add possibility to use default endpoint of the rpmsg device")
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
---
 drivers/rpmsg/rpmsg_char.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 0850ae34fb88..562d545ac0d3 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -76,7 +76,8 @@ int rpmsg_chrdev_eptdev_destroy(struct device *dev, void *data)
 
 	mutex_lock(&eptdev->ept_lock);
 	if (eptdev->ept) {
-		rpmsg_destroy_ept(eptdev->ept);
+		if (!eptdev->default_ept)
+			rpmsg_destroy_ept(eptdev->ept);
 		eptdev->ept = NULL;
 	}
 	mutex_unlock(&eptdev->ept_lock);
-- 
2.34.1