linux-kernel - [PATCH 3.16 68/72] usb: iowarrior: fix deadlock on disconnect

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1575813165.392564361@decadent.org.uk>
Date:   Sun, 08 Dec 2019 13:53:52 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Oliver Neukum" <oneukum@...e.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        syzbot+a64a382964bf6c71a9c0@...kaller.appspotmail.com
Subject: [PATCH 3.16 68/72] usb: iowarrior: fix deadlock on disconnect

3.16.79-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Oliver Neukum <oneukum@...e.com>

commit c468a8aa790e0dfe0a7f8a39db282d39c2c00b46 upstream.

We have to drop the mutex before we close() upon disconnect()
as close() needs the lock. This is safe to do by dropping the
mutex as intfdata is already set to NULL, so open() will fail.

Fixes: 03f36e885fc26 ("USB: open disconnect race in iowarrior")
Reported-by: syzbot+a64a382964bf6c71a9c0@...kaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@...e.com>
Link: https://lore.kernel.org/r/20190808092728.23417-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/misc/iowarrior.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/usb/misc/iowarrior.c
+++ b/drivers/usb/misc/iowarrior.c
@@ -898,19 +898,20 @@ static void iowarrior_disconnect(struct
 	dev = usb_get_intfdata(interface);
 	mutex_lock(&iowarrior_open_disc_lock);
 	usb_set_intfdata(interface, NULL);
+	/* prevent device read, write and ioctl */
+	dev->present = 0;
 
 	minor = dev->minor;
+	mutex_unlock(&iowarrior_open_disc_lock);
+	/* give back our minor - this will call close() locks need to be dropped at this point*/
 
-	/* give back our minor */
 	usb_deregister_dev(interface, &iowarrior_class);
 
 	mutex_lock(&dev->mutex);
 
 	/* prevent device read, write and ioctl */
-	dev->present = 0;
 
 	mutex_unlock(&dev->mutex);
-	mutex_unlock(&iowarrior_open_disc_lock);
 
 	if (dev->opened) {
 		/* There is a process that holds a filedescriptor to the device ,