[PATCH] hvc_console: Don't access hvc_task if not initialised

Amit Shah
2011-03-24T07:30:22Z

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. Ensure hvc is initialised by checking for a non-NULL hvc_task
before waking up the hvc thread.

This was found by an autotest run for virtio_console without having a
console backend.

CC: stable@kernel.org
Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
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);
}
--
1.7.4