linux/drivers/net/slip
Duoming Zhou ec4eb8a86a drivers: net: slip: fix NPD bug in sl_tx_timeout()
When a slip driver is detaching, the slip_close() will act to
cleanup necessary resources and sl->tty is set to NULL in
slip_close(). Meanwhile, the packet we transmit is blocked,
sl_tx_timeout() will be called. Although slip_close() and
sl_tx_timeout() use sl->lock to synchronize, we don`t judge
whether sl->tty equals to NULL in sl_tx_timeout() and the
null pointer dereference bug will happen.

   (Thread 1)                 |      (Thread 2)
                              | slip_close()
                              |   spin_lock_bh(&sl->lock)
                              |   ...
...                           |   sl->tty = NULL //(1)
sl_tx_timeout()               |   spin_unlock_bh(&sl->lock)
  spin_lock(&sl->lock);       |
  ...                         |   ...
  tty_chars_in_buffer(sl->tty)|
    if (tty->ops->..) //(2)   |
    ...                       |   synchronize_rcu()

We set NULL to sl->tty in position (1) and dereference sl->tty
in position (2).

This patch adds check in sl_tx_timeout(). If sl->tty equals to
NULL, sl_tx_timeout() will goto out.

Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20220405132206.55291-1-duoming@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-06 23:00:16 -07:00
..
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
slhc.c net: slip: remove leading spaces before tabs 2021-05-20 15:10:57 -07:00
slip.c drivers: net: slip: fix NPD bug in sl_tx_timeout() 2022-04-06 23:00:16 -07:00
slip.h slip: fix macro redefine warning 2021-11-23 11:38:13 +00:00