Messages in this thread Patch in this message | | | Date | Mon, 21 Aug 2017 22:45:07 +0300 | From | "Michael S. Tsirkin" <> | Subject | [PATCH] vhost: fix end of range for access_ok |
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During access_ok checks, addr increases as we iterate over the data structure, thus addr + len - 1 will point beyond the end of region we are translating. Harmless since we then verify that the region covers addr, but let's not waste cpu cycles.
Reported-by: Koichiro Den <den@klaipeden.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> ---
Lightly tested, would appreciate an ack from reporter.
drivers/vhost/vhost.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index e4613a3..ecd70e4 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1176,7 +1176,7 @@ static int iotlb_access_ok(struct vhost_virtqueue *vq, { const struct vhost_umem_node *node; struct vhost_umem *umem = vq->iotlb; - u64 s = 0, size, orig_addr = addr; + u64 s = 0, size, orig_addr = addr, last = addr + len - 1; if (vhost_vq_meta_fetch(vq, addr, len, type)) return true; @@ -1184,7 +1184,7 @@ static int iotlb_access_ok(struct vhost_virtqueue *vq, while (len > s) { node = vhost_umem_interval_tree_iter_first(&umem->umem_tree, addr, - addr + len - 1); + last); if (node == NULL || node->start > addr) { vhost_iotlb_miss(vq, addr, access); return false; -- MST
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