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virtio: console: Prevent userspace from submitting NULL buffers

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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 <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
CC: stable@kernel.org
This commit is contained in:
Amit Shah 2010-09-14 13:26:16 +05:30 committed by Rusty Russell
parent 6df7aadcd9
commit 65745422a8
1 changed files with 4 additions and 0 deletions
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4
drivers/char/virtio_console.c
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@ -596,6 +596,10 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
ssize_t ret; ssize_t ret;
bool nonblock; bool nonblock;
/* Userspace could be out to fool us */
if (!count)
return 0;
port = filp->private_data; port = filp->private_data;
nonblock = filp->f_flags & O_NONBLOCK; nonblock = filp->f_flags & O_NONBLOCK;