block/nbd: check that received handle is valid

If we don't have active request, that waiting for this handle to be
received, we should report an error.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210902103805.25686-6-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

1 files changed, 3 insertions, 8 deletions

diff --git a/block/nbd.c b/block/nbd.c
index 8ff6daf..5ef462d 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -58,6 +58,7 @@ typedef struct {
     Coroutine *coroutine;
     uint64_t offset;        /* original offset of the request */
     bool receiving;         /* sleeping in the yield in nbd_receive_replies */
+    bool reply_possible;    /* reply header not yet received */
 } NBDClientRequest;
 
 typedef enum NBDClientState {
@@ -415,14 +416,7 @@ static coroutine_fn int nbd_receive_replies(BDRVNBDState *s, uint64_t handle)
             return 0;
         }
         ind2 = HANDLE_TO_INDEX(s, s->reply.handle);
-        if (ind2 >= MAX_NBD_REQUESTS || !s->requests[ind2].coroutine) {
-            /*
-             * We only check that ind2 request exists. But don't check
-             * whether it is now waiting for the reply header or
-             * not. We can't just check s->requests[ind2].receiving:
-             * ind2 request may wait in trying to lock
-             * receive_mutex. So that's a TODO.
-             */
+        if (ind2 >= MAX_NBD_REQUESTS || !s->requests[ind2].reply_possible) {
             nbd_channel_error(s, -EINVAL);
             return -EINVAL;
         }
@@ -468,6 +462,7 @@ static int nbd_co_send_request(BlockDriverState *bs,
     s->requests[i].coroutine = qemu_coroutine_self();
     s->requests[i].offset = request->from;
     s->requests[i].receiving = false;
+    s->requests[i].reply_possible = true;
 
     request->handle = INDEX_TO_HANDLE(s, i);