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authorPeter Hurley <peter@hurleysoftware.com>2014-11-05 12:12:49 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-05 18:24:10 -0800
commit55199ea3bd2e53007715d544fb9094cbbdda1597 (patch)
tree89f757f6bdb5d7b421d4c099ca70b73eb62c64b1
parent216030ec55e08646be629ee32725c0189ad74c9a (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.c7
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)