Messages in this thread Patch in this message | | | Date | Sun, 17 Mar 2013 14:46:09 +0200 | From | "Michael S. Tsirkin" <> | Subject | [PATCH net] vhost/net: fix heads usage of ubuf_info |
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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 ---
Rusty's working on switching to allocating ubufs dynamically but that's not 3.9 material. This patch is against latest net master, needed for 3.9-rc2 and older kernels.
drivers/vhost/net.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 959b1cd..ec6fb3f 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -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; -- MST
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