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| author | Johan Hovold <johan@kernel.org> | 2017-11-03 15:30:52 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-28 16:00:50 +0100 |
| commit | eb281683621b71ab9710d9dccbbef0c2e1769c97 (patch) | |
| tree | e0c2fe0401613f425edf067490108a0519915a9f /drivers/tty/serdev | |
| parent | 0ff3ab701963a845d52337ded7eebf2d1a14fe00 (diff) | |
| download | linux-eb281683621b71ab9710d9dccbbef0c2e1769c97.tar.bz2 | |
serdev: ttyport: add missing receive_buf sanity checks
The receive_buf tty-port callback should return the number of bytes
accepted and must specifically never return a negative errno (or a value
larger than the buffer size) to the tty layer.
A serdev driver not providing a receive_buf callback would currently
cause the flush_to_ldisc() worker to spin in a tight loop when the tty
buffer pointers are incremented with -EINVAL (-22) after data has been
received.
A serdev driver occasionally returning a negative errno (or a too large
byte count) could cause information leaks or crashes when accessing
memory outside the tty buffers in consecutive callbacks.
Fixes: cd6484e1830b ("serdev: Introduce new bus for serial attached devices")
Cc: stable <stable@vger.kernel.org> # 4.11
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serdev')
| -rw-r--r-- | drivers/tty/serdev/serdev-ttyport.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c index ce7ad0acee7a..09fbdd52a561 100644 --- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -27,11 +27,22 @@ static int ttyport_receive_buf(struct tty_port *port, const unsigned char *cp, { struct serdev_controller *ctrl = port->client_data; struct serport *serport = serdev_controller_get_drvdata(ctrl); + int ret; if (!test_bit(SERPORT_ACTIVE, &serport->flags)) return 0; - return serdev_controller_receive_buf(ctrl, cp, count); + ret = serdev_controller_receive_buf(ctrl, cp, count); + + dev_WARN_ONCE(&ctrl->dev, ret < 0 || ret > count, + "receive_buf returns %d (count = %zu)\n", + ret, count); + if (ret < 0) + return 0; + else if (ret > count) + return count; + + return ret; } static void ttyport_write_wakeup(struct tty_port *port) |