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vhost/net: fix heads usage of ubuf_info 

ubuf info allocator uses guest controlled head as an index,
so a malicious guest could put the same head entry in the ring twice,
and we will get two callbacks on the same value.
To fix use upend_idx which is guaranteed to be unique.

Reported-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: stable@kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin 2013-03-17 02:46:09 +00:00 committed by David S. Miller
parent 3d84fa98ac
commit 46aa92d1ba
1 changed files with 2 additions and 1 deletions
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3
drivers/vhost/net.c
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@ -339,7 +339,8 @@ static void handle_tx(struct vhost_net *net)
msg.msg_controllen = 0;
ubufs = NULL;
} else {
struct ubuf_info *ubuf = &vq->ubuf_info[head];
struct ubuf_info *ubuf;
ubuf = vq->ubuf_info + vq->upend_idx;
vq->heads[vq->upend_idx].len =
VHOST_DMA_IN_PROGRESS;