patch "mei: bus: fix unlink on bus in error path" added to char-misc-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    mei: bus: fix unlink on bus in error path

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


From a43866856125c3c432e2fbb6cc63cee1539ec4a7 Mon Sep 17 00:00:00 2001
From: Alexander Usyskin <alexander.usyskin@intel.com>
Date: Tue, 13 Dec 2022 00:02:46 +0200
Subject: mei: bus: fix unlink on bus in error path

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@vger.kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Reviewed-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20221212220247.286019-1-tomas.winkler@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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 4a08b624910a..a81b890c7ee6 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -702,13 +702,15 @@ 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);
@@ -758,7 +760,7 @@ 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;
 	}
@@ -785,6 +787,9 @@ int mei_cldev_enable(struct mei_cl_device *cldev)
 	}
 
 out:
+	if (ret)
+		mei_cl_unlink(cl);
+notlinked:
 	mutex_unlock(&bus->device_lock);
 
 	return ret;
@@ -1277,7 +1282,6 @@ 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);
 }
-- 
2.39.1