From: Michael S. Tsirkin <mst@redhat.com>
Date: Mon, 26 Nov 2012 05:57:27 +0000 (+0000)
Subject: vhost: fix length for cross region descriptor
X-Git-Tag: v3.2.40~16
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=e188567f35fe514253b2e46a31cf03272ab8c030;p=thirdparty%2Fkernel%2Fstable.git

vhost: fix length for cross region descriptor

commit bd97120fc3d1a11f3124c7c9ba1d91f51829eb85 upstream.

If a single descriptor crosses a region, the
second chunk length should be decremented
by size translated so far, instead it includes
the full descriptor length.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index ae66278e4dcf2..be32b1ba8fa6b 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1073,7 +1073,7 @@ static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
 		}
 		_iov = iov + ret;
 		size = reg->memory_size - addr + reg->guest_phys_addr;
-		_iov->iov_len = min((u64)len, size);
+		_iov->iov_len = min((u64)len - s, size);
 		_iov->iov_base = (void __user *)(unsigned long)
 			(reg->userspace_addr + addr - reg->guest_phys_addr);
 		s += size;