Patch "can: etas_es58x: es58x_fd_rx_event_msg(): initialize rx_event_msg before calling es58x_check_msg_len()" has been added to the 5.16-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    can: etas_es58x: es58x_fd_rx_event_msg(): initialize rx_event_msg before calling es58x_check_msg_len()

to the 5.16-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     can-etas_es58x-es58x_fd_rx_event_msg-initialize-rx_e.patch
and it can be found in the queue-5.16 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7aa0ee69864ce848c8dfac3b6a75776404319bdf
Author: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
Date:   Sun Mar 6 19:13:02 2022 +0900

    can: etas_es58x: es58x_fd_rx_event_msg(): initialize rx_event_msg before calling es58x_check_msg_len()
    
    [ Upstream commit 7a8cd7c0ee823a1cc893ab3feaa23e4b602bfb9a ]
    
    Function es58x_fd_rx_event() invokes the es58x_check_msg_len() macro:
    
    |       ret = es58x_check_msg_len(es58x_dev->dev, *rx_event_msg, msg_len);
    
    While doing so, it dereferences an uninitialized
    variable: *rx_event_msg.
    
    This is actually harmless because es58x_check_msg_len() only uses
    preprocessor macros (sizeof() and __stringify()) on
    *rx_event_msg. c.f. [1].
    
    Nonetheless, this pattern is confusing so the lines are reordered to
    make sure that rx_event_msg is correctly initialized.
    
    This patch also fixes a false positive warning reported by cppcheck:
    
    | cppcheck possible warnings: (new ones prefixed by >>, may not be real problems)
    |
    |    In file included from drivers/net/can/usb/etas_es58x/es58x_fd.c:
    | >> drivers/net/can/usb/etas_es58x/es58x_fd.c:174:8: warning: Uninitialized variable: rx_event_msg [uninitvar]
    |     ret = es58x_check_msg_len(es58x_dev->dev, *rx_event_msg, msg_len);
    |           ^
    
    [1] https://elixir.bootlin.com/linux/v5.16/source/drivers/net/can/usb/etas_es58x/es58x_core.h#L467
    
    Link: https://lore.kernel.org/all/20220306101302.708783-1-mailhol.vincent@xxxxxxxxxx
    Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
    Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/can/usb/etas_es58x/es58x_fd.c b/drivers/net/can/usb/etas_es58x/es58x_fd.c
index 4f0cae29f4d8..b71d1530638b 100644
--- a/drivers/net/can/usb/etas_es58x/es58x_fd.c
+++ b/drivers/net/can/usb/etas_es58x/es58x_fd.c
@@ -171,12 +171,11 @@ static int es58x_fd_rx_event_msg(struct net_device *netdev,
 	const struct es58x_fd_rx_event_msg *rx_event_msg;
 	int ret;
 
+	rx_event_msg = &es58x_fd_urb_cmd->rx_event_msg;
 	ret = es58x_check_msg_len(es58x_dev->dev, *rx_event_msg, msg_len);
 	if (ret)
 		return ret;
 
-	rx_event_msg = &es58x_fd_urb_cmd->rx_event_msg;
-
 	return es58x_rx_err_msg(netdev, rx_event_msg->error_code,
 				rx_event_msg->event_code,
 				get_unaligned_le64(&rx_event_msg->timestamp));