diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2014-11-05 12:12:49 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-05 18:24:10 -0800 |
| commit | 55199ea3bd2e53007715d544fb9094cbbdda1597 (patch) | |
| tree | 89f757f6bdb5d7b421d4c099ca70b73eb62c64b1 | |
| parent | 216030ec55e08646be629ee32725c0189ad74c9a (diff) | |
pty: Always return -EIO if slave BSD pty opened first
Opening the slave BSD pty first already returns -EIO from the slave
pty_open(), which in turn causes the newly installed tty pair to be
released before returning from tty_open(). However, this can also
cause a parallel master BSD pty open to fail because the pty pair
destruction may already been taking place in tty_release().
Failing at driver->install() if the slave pty is opened first ensures
that a pty master open cannot fail, because the driver tables will
not have been updated so tty_driver_lookup_tty() won't find the
master pty (and attempt to "re-open" it).
In turn, this guarantees that any tty with a tty->count == 0 is
in final close (rather than never opened).
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/pty.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 7a1a53819e22..bdb8fd1a2026 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -383,6 +383,10 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, int idx = tty->index; int retval = -ENOMEM; + /* Opening the slave first has always returned -EIO */ + if (driver->subtype != PTY_TYPE_MASTER) + return -EIO; + ports[0] = kmalloc(sizeof **ports, GFP_KERNEL); ports[1] = kmalloc(sizeof **ports, GFP_KERNEL); if (!ports[0] || !ports[1]) @@ -419,8 +423,6 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, * Everything allocated ... set up the o_tty structure. */ tty_driver_kref_get(driver->other); - if (driver->subtype == PTY_TYPE_MASTER) - o_tty->count++; /* Establish the links in both directions */ tty->link = o_tty; o_tty->link = tty; @@ -432,6 +434,7 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, tty_driver_kref_get(driver); tty->count++; + o_tty->count++; return 0; err_free_termios: if (legacy) |