Re: hvc_console: Don't access hvc_task if not initialised
From: Milton Miller <hidden>
Date: 2011-03-24 14:58:17
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[removed stable list from discussion] On Thu, 24 Mar 2011 07:29:58 -0000, Amit Shah wrote:
hvc_open() can be called without having any backing device. This results in a call to hvc_kick() which calls wake_up_process on a NULL pointer.
How is hvc_open called without a hvc_driver registered to the tty layer?
Ensure hvc is initialised by checking for a non-NULL hvc_task before waking up the hvc thread.
No if the task is missing the subsystem is really stuck. Put a check in open and refuse to open.
This was found by an autotest run for virtio_console without having a console backend.
stack trace please
quoted hunk ↗ jump to hunk
CC: stable@kernel.org Signed-off-by: Amit Shah <redacted> --- drivers/tty/hvc/hvc_console.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index e9cba13..b2cb5cc 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c@@ -286,6 +286,9 @@ EXPORT_SYMBOL_GPL(hvc_instantiate); /* Wake the sleeping khvcd */ void hvc_kick(void) { + if (!hvc_task) + return; + hvc_kicked = 1; wake_up_process(hvc_task); }