[Qemu-devel] [PATCH 93/99] nbd/server: Reject 0-length block status request

[Michael Roth]

From: Eric Blake <address@hidden>

The NBD spec says that behavior is unspecified if the client
requests 0 length for block status; but since the structured
reply is documenting as returning a non-zero length, it's
easier to just diagnose this with an EINVAL error than to
figure out what to return.

CC: address@hidden
Signed-off-by: Eric Blake <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
(cherry picked from commit d8b20291cba6aa9bb295885a34f2b5f05d59d1b2)
Signed-off-by: Michael Roth <address@hidden>
---
 nbd/server.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/nbd/server.c b/nbd/server.c
index 9e1f227178..493a926e06 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -2007,6 +2007,10 @@ static coroutine_fn int nbd_handle_request(NBDClient 
*client,
                                       "discard failed", errp);
 
     case NBD_CMD_BLOCK_STATUS:
+        if (!request->len) {
+            return nbd_send_generic_reply(client, request->handle, -EINVAL,
+                                          "need non-zero length", errp);
+        }
         if (client->export_meta.valid && client->export_meta.base_allocation) {
             return nbd_co_send_block_status(client, request->handle,
                                             blk_bs(exp->blk), request->from,
-- 
2.17.1