diff options
authorJohan Hovold <johan@kernel.org>2015-03-04 10:39:06 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-07 03:44:14 +0100
commit79fbf4a550ed6a22e1ae1516113e6c7fa5d56a53 (patch)
parentUSB: serial: fix infinite wait_until_sent timeout (diff)
TTY: fix tty_wait_until_sent on 64-bit machines
Fix overflow bug in tty_wait_until_sent on 64-bit machines, where an infinite timeout (0) would be passed to the underlying tty-driver's wait_until_sent-operation as a negative timeout (-1), causing it to return immediately. This manifests itself for example as tcdrain() returning immediately, drivers not honouring the drain flags when setting terminal attributes, or even dropped data on close as a requested infinite closing-wait timeout would be ignored. The first symptom was reported by Asier LLANO who noted that tcdrain() returned prematurely when using the ftdi_sio usb-serial driver. Fix this by passing 0 rather than MAX_SCHEDULE_TIMEOUT (LONG_MAX) to the underlying tty driver. Note that the serial-core wait_until_sent-implementation is not affected by this bug due to a lucky chance (comparison to an unsigned maximum timeout), and neither is the cyclades one that had an explicit check for negative timeouts, but all other tty drivers appear to be affected. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable <stable@vger.kernel.org> # v2.6.12 Reported-by: ZIV-Asier Llano Palacios <asier.llano@cgglobal.com> Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index a5cf253b2544..89ae23ac9ae6 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -217,11 +217,17 @@ void tty_wait_until_sent(struct tty_struct *tty, long timeout)
if (!timeout)
if (wait_event_interruptible_timeout(tty->write_wait,
- !tty_chars_in_buffer(tty), timeout) >= 0) {
- if (tty->ops->wait_until_sent)
- tty->ops->wait_until_sent(tty, timeout);
+ !tty_chars_in_buffer(tty), timeout) < 0) {
+ return;
+ if (timeout == MAX_SCHEDULE_TIMEOUT)
+ timeout = 0;
+ if (tty->ops->wait_until_sent)
+ tty->ops->wait_until_sent(tty, timeout);