[PATCH 4.9 08/44] vhost: reject zero size iova range

[Greg Kroah-Hartman]

From: Jason Wang <jasow...@redhat.com>

[ Upstream commit 813dbeb656d6c90266f251d8bd2b02d445afa63f ]

We used to accept zero size iova range which will lead a infinite loop
in translate_desc(). Fixing this by failing the request in this case.

Reported-by: syzbot+d21e6e297322a900c...@syzkaller.appspotmail.com
Fixes: 6b1e6cc7 ("vhost: new device IOTLB API")
Signed-off-by: Jason Wang <jasow...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/vhost/vhost.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -863,8 +863,12 @@ static int vhost_new_umem_range(struct v
                                u64 start, u64 size, u64 end,
                                u64 userspace_addr, int perm)
 {
-       struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
+       struct vhost_umem_node *tmp, *node;
 
+       if (!size)
+               return -EFAULT;
+
+       node = kmalloc(sizeof(*node), GFP_ATOMIC);
        if (!node)
                return -ENOMEM;