From 65745422a898741ee0e7068ef06624ab06e8aefa Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Tue, 14 Sep 2010 13:26:16 +0530 Subject: [PATCH] virtio: console: Prevent userspace from submitting NULL buffers A userspace could submit a buffer with 0 length to be written to the host. Prevent such a situation. This was not needed previously, but recent changes in the way write() works exposed this condition to trigger a virtqueue event to the host, causing a NULL buffer to be sent across. Signed-off-by: Amit Shah Signed-off-by: Rusty Russell CC: stable@kernel.org --- drivers/char/virtio_console.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 2f2e31b58b34..c810481a5bc2 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -596,6 +596,10 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf, ssize_t ret; bool nonblock; + /* Userspace could be out to fool us */ + if (!count) + return 0; + port = filp->private_data; nonblock = filp->f_flags & O_NONBLOCK;