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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Jia-Ju Bai" <baijiaju1990@gmail.com>,
        "Johan Hovold" <johan@kernel.org>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
Message-ID: <lsq.1528380321.7574378@decadent.org.uk>
Subject: [PATCH 3.16 084/410] USB: serial: io_edgeport: fix possible
 sleep-in-atomic
In-Reply-To: <lsq.1528380320.647747352@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jia-Ju Bai <baijiaju1990@gmail.com>

commit c7b8f77872c73f69a16528a9eb87afefcccdc18b upstream.

According to drivers/usb/serial/io_edgeport.c, the driver may sleep
under a spinlock.
The function call path is:
edge_bulk_in_callback (acquire the spinlock)
   process_rcvd_data
     process_rcvd_status
       change_port_settings
         send_iosp_ext_cmd
           write_cmd_usb
             usb_kill_urb --> may sleep

To fix it, the redundant usb_kill_urb() is removed from the error path
after usb_submit_urb() fails.

This possible bug is found by my static analysis tool (DSAC) and checked
by my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/usb/serial/io_edgeport.c | 1 -
 1 file changed, 1 deletion(-)

--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -2219,7 +2219,6 @@ static int write_cmd_usb(struct edgeport
 		/* something went wrong */
 		dev_err(dev, "%s - usb_submit_urb(write command) failed, status = %d\n",
 			__func__, status);
-		usb_kill_urb(urb);
 		usb_free_urb(urb);
 		atomic_dec(&CmdUrbs);
 		return status;