linux-kernel - [char-misc 1/2] mei: bus: fix unlink on bus in error path

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Date:   Tue, 13 Dec 2022 00:02:46 +0200
From:   Tomas Winkler <tomas.winkler@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        Vitaly Lubart <vitaly.lubart@...el.com>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc 1/2] mei: bus: fix unlink on bus in error path

From: Alexander Usyskin <alexander.usyskin@...el.com>

Unconditional call to mei_cl_unlink in mei_cl_bus_dev_release leads
to call of the mei_cl_unlink without corresponding mei_cl_link.
This leads to miscalculation of open_handle_count (decrease without
increase).

Call unlink in mei_cldev_enable fail path and remove blanket unlink
from mei_cl_bus_dev_release.

Fixes: 34f1166afd67 ("mei: bus: need to unlink client before freeing")
Cc: <stable@...r.kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
Reviewed-by: Tomas Winkler <tomas.winkler@...el.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 drivers/misc/mei/bus.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index fdb5f7331695..3d24bdb02f0f 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -685,13 +685,15 @@ void *mei_cldev_dma_map(struct mei_cl_device *cldev, u8 buffer_id, size_t size)
 	if (cl->state == MEI_FILE_UNINITIALIZED) {
 		ret = mei_cl_link(cl);
 		if (ret)
-			goto out;
+			goto notlinked;
 		/* update pointers */
 		cl->cldev = cldev;
 	}
 
 	ret = mei_cl_dma_alloc_and_map(cl, NULL, buffer_id, size);
-out:
+	if (ret)
+		mei_cl_unlink(cl);
+notlinked:
 	mutex_unlock(&bus->device_lock);
 	if (ret)
 		return ERR_PTR(ret);
@@ -741,7 +743,7 @@ int mei_cldev_enable(struct mei_cl_device *cldev)
 	if (cl->state == MEI_FILE_UNINITIALIZED) {
 		ret = mei_cl_link(cl);
 		if (ret)
-			goto out;
+			goto notlinked;
 		/* update pointers */
 		cl->cldev = cldev;
 	}
@@ -768,6 +770,9 @@ int mei_cldev_enable(struct mei_cl_device *cldev)
 	}
 
 out:
+	if (ret)
+		mei_cl_unlink(cl);
+notlinked:
 	mutex_unlock(&bus->device_lock);
 
 	return ret;
@@ -1135,7 +1140,6 @@ static void mei_cl_bus_dev_release(struct device *dev)
 	mei_cl_flush_queues(cldev->cl, NULL);
 	mei_me_cl_put(cldev->me_cl);
 	mei_dev_bus_put(cldev->bus);
-	mei_cl_unlink(cldev->cl);
 	kfree(cldev->cl);
 	kfree(cldev);
 }
-- 
2.38.1