On Mon, 05 Feb 2024 19:26, Stefan Hajnoczi <stefa...@redhat.com> wrote:
Hanna Czenczek <hre...@redhat.com> noted that the array index in
virtio_blk_dma_restart_cb() is not bounds-checked:

 g_autofree VirtIOBlockReq **vq_rq = g_new0(VirtIOBlockReq *, num_queues);
 ...
 while (rq) {
     VirtIOBlockReq *next = rq->next;
     uint16_t idx = virtio_get_queue_index(rq->vq);

     rq->next = vq_rq[idx];
                ^^^^^^^^^^

The code is correct because both rq->vq and vq_rq[] depend on
num_queues, but this is indirect and not 100% obvious. Add an assertion.

This sentence could be useful as an inline comment too.


Suggested-by: Hanna Czenczek <hre...@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
hw/block/virtio-blk.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index a0735a9bca..f3193f4b75 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -1209,6 +1209,7 @@ static void virtio_blk_dma_restart_cb(void *opaque, bool 
running,
        VirtIOBlockReq *next = rq->next;
        uint16_t idx = virtio_get_queue_index(rq->vq);

+        assert(idx < num_queues);
        rq->next = vq_rq[idx];
        vq_rq[idx] = rq;
        rq = next;
--
2.43.0


Reviewed-by: Manos Pitsidianakis <manos.pitsidiana...@linaro.org>

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