pty: fix possible use after free of tty->driver_data

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[ Upstream commit 2831c89f42 ]

This change fixes a bug for a corner case where we have the the last
release from a pty master/slave coming from a previously opened /dev/tty
file. When this happens, the tty->driver_data can be stale, due to all
ptmx or pts/N files having already been closed before (and thus the inode
related to these files, which tty->driver_data points to, being already
freed/destroyed).

The fix here is to keep a reference on the opened master ptmx inode.
We maintain the inode referenced until the final pty_unix98_shutdown,
and only pass this inode to devpts_kill_index.

Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
Cc: <stable@vger.kernel.org> # 2.6.29+
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

...

This commit is contained in:

Herton R. Krzesinski 2016-01-11 12:07:43 -02:00 • committed by Sasha Levin

parent f46aa4a4ac

commit f8b4df5f7d

1 changed files with 17 additions and 1 deletions

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drivers/tty/pty.c

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