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Revision 0ace17d56824165c7f4c68785d6b58971db954dd authored by Richard Palethorpe on 21 January 2020, 13:42:58 UTC, committed by David S. Miller on 22 January 2020, 19:32:03 UTC 
can, slip: Protect tty->disc_data in write_wakeup and close with RCU
 
write_wakeup can happen in parallel with close/hangup where tty->disc_data
is set to NULL and the netdevice is freed thus also freeing
disc_data. write_wakeup accesses disc_data so we must prevent close from
freeing the netdev while write_wakeup has a non-NULL view of
tty->disc_data.

We also need to make sure that accesses to disc_data are atomic. Which can
all be done with RCU.

This problem was found by Syzkaller on SLCAN, but the same issue is
reproducible with the SLIP line discipline using an LTP test based on the
Syzkaller reproducer.

A fix which didn't use RCU was posted by Hillf Danton.

Fixes: 661f7fda21b1 ("slip: Fix deadlock in write_wakeup")
Fixes: a8e83b17536a ("slcan: Port write_wakeup deadlock fix from slip")
Reported-by: syzbot+017e491ae13c0068598a@syzkaller.appspotmail.com
Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Tyler Hall <tylerwhall@gmail.com>
Cc: linux-can@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: syzkaller@googlegroups.com
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 58c8db9
Raw File
Kconfig 
# SPDX-License-Identifier: GPL-2.0-only
config UDF_FS
	tristate "UDF file system support"
	select CRC_ITU_T
	select NLS
	help
	  This is a file system used on some CD-ROMs and DVDs. Since the
	  file system is supported by multiple operating systems and is more
	  compatible with standard unix file systems, it is also suitable for
	  removable USB disks. Say Y if you intend to mount DVD discs or CDRW's
	  written in packet mode, or if you want to use UDF for removable USB
	  disks. Please read <file:Documentation/filesystems/udf.txt>.

	  To compile this file system support as a module, choose M here: the
	  module will be called udf.

	  If unsure, say N.
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