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net: hso: fix null-ptr-deref during tty device unregistration
Multiple ttys try to claim the same the minor number causing a double
unregistration of the same device. The first unregistration succeeds
but the next one results in a null-ptr-deref.
The get_free_serial_index() function returns an available minor number
but doesn't assign it immediately. The assignment is done by the caller
later. But before this assignment, calls to get_free_serial_index()
would return the same minor number.
Fix this by modifying get_free_serial_index to assign the minor number
immediately after one is found to be and rename it to obtain_minor()
to better reflect what it does. Similary, rename set_serial_by_index()
to release_minor() and modify it to free up the minor number of the
given hso_serial. Every obtain_minor() should have corresponding
release_minor() call.
Fixes: 72dc1c096c
("HSO: add option hso driver")
Reported-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com
Tested-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
5d1dbacde1
commit
8a12f88361
1 changed files with 12 additions and 21 deletions
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@ -611,7 +611,7 @@ static struct hso_serial *get_serial_by_index(unsigned index)
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return serial;
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return serial;
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}
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}
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static int get_free_serial_index(void)
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static int obtain_minor(struct hso_serial *serial)
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{
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{
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int index;
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int index;
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unsigned long flags;
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unsigned long flags;
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@ -619,8 +619,10 @@ static int get_free_serial_index(void)
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spin_lock_irqsave(&serial_table_lock, flags);
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spin_lock_irqsave(&serial_table_lock, flags);
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for (index = 0; index < HSO_SERIAL_TTY_MINORS; index++) {
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for (index = 0; index < HSO_SERIAL_TTY_MINORS; index++) {
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if (serial_table[index] == NULL) {
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if (serial_table[index] == NULL) {
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serial_table[index] = serial->parent;
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serial->minor = index;
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spin_unlock_irqrestore(&serial_table_lock, flags);
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spin_unlock_irqrestore(&serial_table_lock, flags);
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return index;
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return 0;
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}
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}
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}
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}
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spin_unlock_irqrestore(&serial_table_lock, flags);
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spin_unlock_irqrestore(&serial_table_lock, flags);
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@ -629,15 +631,12 @@ static int get_free_serial_index(void)
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return -1;
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return -1;
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}
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}
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static void set_serial_by_index(unsigned index, struct hso_serial *serial)
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static void release_minor(struct hso_serial *serial)
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{
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{
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unsigned long flags;
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unsigned long flags;
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spin_lock_irqsave(&serial_table_lock, flags);
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spin_lock_irqsave(&serial_table_lock, flags);
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if (serial)
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serial_table[serial->minor] = NULL;
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serial_table[index] = serial->parent;
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else
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serial_table[index] = NULL;
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spin_unlock_irqrestore(&serial_table_lock, flags);
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spin_unlock_irqrestore(&serial_table_lock, flags);
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}
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}
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@ -2230,6 +2229,7 @@ static int hso_stop_serial_device(struct hso_device *hso_dev)
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static void hso_serial_tty_unregister(struct hso_serial *serial)
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static void hso_serial_tty_unregister(struct hso_serial *serial)
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{
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{
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tty_unregister_device(tty_drv, serial->minor);
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tty_unregister_device(tty_drv, serial->minor);
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release_minor(serial);
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}
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}
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static void hso_serial_common_free(struct hso_serial *serial)
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static void hso_serial_common_free(struct hso_serial *serial)
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@ -2253,24 +2253,22 @@ static void hso_serial_common_free(struct hso_serial *serial)
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static int hso_serial_common_create(struct hso_serial *serial, int num_urbs,
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static int hso_serial_common_create(struct hso_serial *serial, int num_urbs,
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int rx_size, int tx_size)
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int rx_size, int tx_size)
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{
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{
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int minor;
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int i;
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int i;
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tty_port_init(&serial->port);
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tty_port_init(&serial->port);
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minor = get_free_serial_index();
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if (obtain_minor(serial))
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if (minor < 0)
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goto exit2;
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goto exit2;
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/* register our minor number */
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/* register our minor number */
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serial->parent->dev = tty_port_register_device_attr(&serial->port,
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serial->parent->dev = tty_port_register_device_attr(&serial->port,
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tty_drv, minor, &serial->parent->interface->dev,
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tty_drv, serial->minor, &serial->parent->interface->dev,
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serial->parent, hso_serial_dev_groups);
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serial->parent, hso_serial_dev_groups);
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if (IS_ERR(serial->parent->dev))
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if (IS_ERR(serial->parent->dev)) {
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release_minor(serial);
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goto exit2;
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goto exit2;
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}
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/* fill in specific data for later use */
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serial->minor = minor;
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serial->magic = HSO_SERIAL_MAGIC;
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serial->magic = HSO_SERIAL_MAGIC;
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spin_lock_init(&serial->serial_lock);
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spin_lock_init(&serial->serial_lock);
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serial->num_rx_urbs = num_urbs;
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serial->num_rx_urbs = num_urbs;
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@ -2667,9 +2665,6 @@ static struct hso_device *hso_create_bulk_serial_device(
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serial->write_data = hso_std_serial_write_data;
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serial->write_data = hso_std_serial_write_data;
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/* and record this serial */
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set_serial_by_index(serial->minor, serial);
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/* setup the proc dirs and files if needed */
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/* setup the proc dirs and files if needed */
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hso_log_port(hso_dev);
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hso_log_port(hso_dev);
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@ -2726,9 +2721,6 @@ struct hso_device *hso_create_mux_serial_device(struct usb_interface *interface,
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serial->shared_int->ref_count++;
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serial->shared_int->ref_count++;
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mutex_unlock(&serial->shared_int->shared_int_lock);
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mutex_unlock(&serial->shared_int->shared_int_lock);
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/* and record this serial */
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set_serial_by_index(serial->minor, serial);
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/* setup the proc dirs and files if needed */
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/* setup the proc dirs and files if needed */
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hso_log_port(hso_dev);
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hso_log_port(hso_dev);
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@ -3113,7 +3105,6 @@ static void hso_free_interface(struct usb_interface *interface)
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cancel_work_sync(&serial_table[i]->async_get_intf);
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cancel_work_sync(&serial_table[i]->async_get_intf);
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hso_serial_tty_unregister(serial);
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hso_serial_tty_unregister(serial);
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kref_put(&serial_table[i]->ref, hso_serial_ref_free);
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kref_put(&serial_table[i]->ref, hso_serial_ref_free);
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set_serial_by_index(i, NULL);
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}
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}
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}
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}
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