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| author | James Woodcock <James.Woodcock@ACULAB.COM> | 2009-02-11 15:06:53 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-03-24 23:20:31 (GMT) |
| commit | 331879fd6f584d60327ba802616d41bfa636b873 (patch) | |
| tree | 0cb4c0b41d16242ea27e2206bc13d9eaeb020bf3 /drivers/usb/serial | |
| parent | 1c27ae671e6b465e04544450276c88f4dba8de60 (diff) | |
| download | linux-331879fd6f584d60327ba802616d41bfa636b873.tar.xz | |
USB: serial: refuse to open recently removed USB Serial devices
A USB-serial converter device is plugged into a system, and a process
opens it's device node. If the device is physically removed whilst the
process still has its device node open, then other processes can
sucessfully open the now non-existent device's node. I would expect
that open() on a device that has been physically removed should return
ENODEV.
This is manifesting itself with getty on my system. I do the following:
1. set up inittab to spawn getty on ttyUSB0, eg:
T1:23:respawn:/sbin/getty -L ttyUSB0 115200 vt100
2. Plug in USB-serial converter cable
3. Wait for a login prompt on a terminal program attached to the serial
cable
4. Login
5. Pull the USB-serial converter cable from the box
6. getty doesn't realise that ttyUSB0 no longer exists as /dev/ttyUSB0
can still be opened.
7. Re-insert the USB-serial converter cable
8. You should no longer get a login prompt over the serial cable, as
the the USB-serial cable now shows up as /dev/ttyUSB1, and getty is
trying to talk to /dev/ttyUSB0.
The attached patch will cause open("/dev/ttyUSB0", O_RDONLY) to return
ENODEV after the USB-serial converter has been pulled. The patch was
created against 2.6.28.1. I can supply it against something else if
needs be. It is fairly simple, so should be OK.
I am using a pl2303 device, although I don't think that makes any
difference.
From: James Woodcock <James.Woodcock@ACULAB.COM>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/serial')
| -rw-r--r-- | drivers/usb/serial/usb-serial.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index 9a26178..7317289 100644 --- a/drivers/usb/serial/usb-serial.c +++ b/drivers/usb/serial/usb-serial.c @@ -204,6 +204,11 @@ static int serial_open (struct tty_struct *tty, struct file *filp) goto bailout_kref_put; } + if (port->serial->disconnected) { + retval = -ENODEV; + goto bailout_kref_put; + } + if (mutex_lock_interruptible(&port->mutex)) { retval = -ERESTARTSYS; goto bailout_kref_put; |