[PATCH] USB Serial: fix use-after-free bug in usb-serial core

From: Greg Kroah-Hartman
Date: Mon Mar 06 2006 - 16:23:43 EST


This fixes a use-after-free bug in the usb-serial core. It is simple to
trigger this (open a usb-serial port, then yank the device out before
closing the port.) Thanks to Stefan Seyfried <seife@xxxxxxx> for
reporting this, and to the slab debugging code which enabled it to be
tracked down.

Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
drivers/usb/serial/usb-serial.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

--- gregkh-2.6.orig/drivers/usb/serial/usb-serial.c
+++ gregkh-2.6/drivers/usb/serial/usb-serial.c
@@ -242,8 +242,10 @@ static void serial_close(struct tty_stru

down(&port->sem);

- if (port->open_count == 0)
- goto out;
+ if (port->open_count == 0) {
+ up(&port->sem);
+ return;
+ }

--port->open_count;
if (port->open_count == 0) {
@@ -260,10 +262,8 @@ static void serial_close(struct tty_stru
module_put(port->serial->type->driver.owner);
}

- kref_put(&port->serial->kref, destroy_serial);
-
-out:
up(&port->sem);
+ kref_put(&port->serial->kref, destroy_serial);
}

static int serial_write (struct tty_struct * tty, const unsigned char *buf, int count)
-
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