From d269d4434c72ed0da3a9b1230c30da82c4918c63 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 5 Jan 2015 16:04:12 +0100 Subject: USB: console: fix uninitialised ldisc semaphore The USB console currently allocates a temporary fake tty which is used to pass terminal settings to the underlying serial driver. The tty struct is not fully initialised, something which can lead to a lockdep warning (or worse) if a serial driver tries to acquire a line-discipline reference: usbserial: USB Serial support registered for pl2303 pl2303 1-2.1:1.0: pl2303 converter detected usb 1-2.1: pl2303 converter now attached to ttyUSB0 INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. CPU: 0 PID: 68 Comm: udevd Tainted: G W 3.18.0-rc5 #10 [] (unwind_backtrace) from [] (show_stack+0x20/0x24) [] (show_stack) from [] (dump_stack+0x24/0x28) [] (dump_stack) from [] (__lock_acquire+0x1e50/0x2004) [] (__lock_acquire) from [] (lock_acquire+0xe4/0x18c) [] (lock_acquire) from [] (ldsem_down_read_trylock+0x78/0x90) [] (ldsem_down_read_trylock) from [] (tty_ldisc_ref+0x24/0x58) [] (tty_ldisc_ref) from [] (usb_serial_handle_dcd_change+0x48/0xe8) [] (usb_serial_handle_dcd_change) from [] (pl2303_read_int_callback+0x210/0x220 [pl2303]) [] (pl2303_read_int_callback [pl2303]) from [] (__usb_hcd_giveback_urb+0x80/0x140) [] (__usb_hcd_giveback_urb) from [] (usb_giveback_urb_bh+0x98/0xd4) [] (usb_giveback_urb_bh) from [] (tasklet_hi_action+0x9c/0x108) [] (tasklet_hi_action) from [] (__do_softirq+0x148/0x42c) [] (__do_softirq) from [] (irq_exit+0xd8/0x114) [] (irq_exit) from [] (__handle_domain_irq+0x84/0xdc) [] (__handle_domain_irq) from [] (omap_intc_handle_irq+0xd8/0xe0) [] (omap_intc_handle_irq) from [] (__irq_svc+0x44/0x7c) Exception stack(0xdf4e7f08 to 0xdf4e7f50) 7f00: debc0b80 df4e7f5c 00000000 00000000 debc0b80 be8da96c 7f20: 00000000 00000128 c000fc84 df4e6000 00000000 df4e7f94 00000004 df4e7f50 7f40: c038ebc0 c038d74c 600f0013 ffffffff [] (__irq_svc) from [] (___sys_sendmsg.part.29+0x0/0x2e0) [] (___sys_sendmsg.part.29) from [] (SyS_sendmsg+0x18/0x1c) [] (SyS_sendmsg) from [] (ret_fast_syscall+0x0/0x48) console [ttyUSB0] enabled Fixes: 36697529b5bb ("tty: Replace ldisc locking with ldisc_sem") Cc: stable Signed-off-by: Johan Hovold --- drivers/usb/serial/console.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/usb/serial/console.c') diff --git a/drivers/usb/serial/console.c b/drivers/usb/serial/console.c index 8d7fc48b1f30..e56f394b58d8 100644 --- a/drivers/usb/serial/console.c +++ b/drivers/usb/serial/console.c @@ -140,6 +140,7 @@ static int usb_console_setup(struct console *co, char *options) tty_port_tty_set(&port->port, tty); tty->driver = usb_serial_tty_driver; tty->index = co->index; + init_ldsem(&tty->ldisc_sem); if (tty_init_termios(tty)) { retval = -ENOMEM; goto free_tty; -- cgit v1.2.3 From 32a4bf2e81ec378e5925d4e069e0677a6c86a6ad Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 5 Jan 2015 16:04:13 +0100 Subject: USB: console: fix potential use after free Use tty kref to release the fake tty in usb_console_setup to avoid use after free if the underlying serial driver has acquired a reference. Note that using the tty destructor release_one_tty requires some more state to be initialised. Fixes: 4a90f09b20f4 ("tty: usb-serial krefs") Cc: stable Signed-off-by: Johan Hovold --- drivers/usb/serial/console.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'drivers/usb/serial/console.c') diff --git a/drivers/usb/serial/console.c b/drivers/usb/serial/console.c index e56f394b58d8..29fa1c3d0089 100644 --- a/drivers/usb/serial/console.c +++ b/drivers/usb/serial/console.c @@ -46,6 +46,8 @@ static struct console usbcons; * ------------------------------------------------------------ */ +static const struct tty_operations usb_console_fake_tty_ops = { +}; /* * The parsing of the command line works exactly like the @@ -137,14 +139,17 @@ static int usb_console_setup(struct console *co, char *options) goto reset_open_count; } kref_init(&tty->kref); - tty_port_tty_set(&port->port, tty); tty->driver = usb_serial_tty_driver; tty->index = co->index; init_ldsem(&tty->ldisc_sem); + INIT_LIST_HEAD(&tty->tty_files); + kref_get(&tty->driver->kref); + tty->ops = &usb_console_fake_tty_ops; if (tty_init_termios(tty)) { retval = -ENOMEM; - goto free_tty; + goto put_tty; } + tty_port_tty_set(&port->port, tty); } /* only call the device specific open if this @@ -162,7 +167,7 @@ static int usb_console_setup(struct console *co, char *options) serial->type->set_termios(tty, port, &dummy); tty_port_tty_set(&port->port, NULL); - kfree(tty); + tty_kref_put(tty); } set_bit(ASYNCB_INITIALIZED, &port->port.flags); } @@ -178,8 +183,8 @@ static int usb_console_setup(struct console *co, char *options) fail: tty_port_tty_set(&port->port, NULL); - free_tty: - kfree(tty); + put_tty: + tty_kref_put(tty); reset_open_count: port->port.count = 0; usb_autopm_put_interface(serial->interface); -- cgit v1.2.3