The patch titled
usb_serial: only allow sysrq on a console port
has been added to the -mm tree. Its filename is
usb_serial-only-allow-sysrq-on-a-console-port.patch
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Subject: usb_serial: only allow sysrq on a console port
From: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
The only time a sysrq should get processed is if the attached device is a
console. This is intended to protect sysrq execution on a host connected
with a terminal program.
Here is the problem scenario:
host A <-- rs232 link --> host B
Host A is using mincom and a usb pl2303 device to connect to host b which
is a linux system with a usb pl2303 device acting as the serial console.
When host B is rebooted the pl2303 emits random junk characters on reset.
These character sequences contain serial break signals most of the time
and when translated to a sysrq have caused host A to get random processes
killed, reboots or power down.
It is true that in this setup with this patch host B might still have the
same problem as host A if you reboot host A. In most cases host A is a
development host which seldom gets rebooted, and you could turn off sysrq
temporarily on host B if you need to reboot host A.
Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/usb/serial/generic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN drivers/usb/serial/generic.c~usb_serial-only-allow-sysrq-on-a-console-port drivers/usb/serial/generic.c
--- a/drivers/usb/serial/generic.c~usb_serial-only-allow-sysrq-on-a-console-port
+++ a/drivers/usb/serial/generic.c
@@ -528,7 +528,7 @@ void usb_serial_generic_unthrottle(struc
int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
{
- if (port->sysrq) {
+ if (port->sysrq && port->console) {
if (ch && time_before(jiffies, port->sysrq)) {
handle_sysrq(ch, tty_port_tty_get(&port->port));
port->sysrq = 0;
_
Patches currently in -mm which might be from jason.wessel@xxxxxxxxxxxxx are
linux-next.patch
pl2303-usb_serial-implement-sysrq-handling-on-break.patch
usb_serial-only-allow-sysrq-on-a-console-port.patch
frv-duplicate-output_buffer-of-e03.patch
kgdb-kgdboc-console-poll-hooks-for-serial_txx9-uart.patch
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