[PULL 4/5] virtiofsd: do_read missing NULL check

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Missing a NULL check if the argument fetch fails.

Fixes: Coverity CID 1413119
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tools/virtiofsd/fuse_lowlevel.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
index 01c418aade..704c0369b2 100644
--- a/tools/virtiofsd/fuse_lowlevel.c
+++ b/tools/virtiofsd/fuse_lowlevel.c
@@ -1116,6 +1116,10 @@ static void do_read(fuse_req_t req, fuse_ino_t nodeid,
         struct fuse_file_info fi;
 
         arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+        if (!arg) {
+            fuse_reply_err(req, EINVAL);
+            return;
+        }
 
         memset(&fi, 0, sizeof(fi));
         fi.fh = arg->fh;
-- 
2.24.1