[ 3.5.y.z extended stable ] Patch "vhost: fix length for cross region descriptor" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Tue Mar 5 18:51:37 UTC 2013

This is a note to let you know that I have just added a patch titled

    vhost: fix length for cross region descriptor

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 192ee54c36212e0dd76988bdda4c0b0afd605c29 Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst at redhat.com>
Date: Mon, 26 Nov 2012 05:57:27 +0000
Subject: [PATCH] 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 at redhat.com>
Acked-by: Jason Wang <jasowang at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 drivers/vhost/vhost.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 112156f..6da514b 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1077,7 +1077,7 @@ 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;

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