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authorAmit Shah <amit.shah@redhat.com>2010-09-14 03:56:16 -0400
committerRusty Russell <rusty@rustcorp.com.au>2010-09-20 21:24:01 -0400
commit65745422a898741ee0e7068ef06624ab06e8aefa (patch)
treeadee25ae37886d79f8319ce69673a75036423c28
parent6df7aadcd9290807c464675098b5dd2dc9da5075 (diff)
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 <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> CC: stable@kernel.org
-rw-r--r--drivers/char/virtio_console.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 2f2e31b58b3..c810481a5bc 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,
596 ssize_t ret; 596 ssize_t ret;
597 bool nonblock; 597 bool nonblock;
598 598
599 /* Userspace could be out to fool us */
600 if (!count)
601 return 0;
602
599 port = filp->private_data; 603 port = filp->private_data;
600 604
601 nonblock = filp->f_flags & O_NONBLOCK; 605 nonblock = filp->f_flags & O_NONBLOCK;