bus: when the first char a server receives isn't the NUL byte immediately fail

diff --git a/src/libsystemd-bus/bus-socket.c b/src/libsystemd-bus/bus-socket.c
index 30e594243d5d62893182f30d21b1600cc22b84c4..82e683a9578724bd9acd2e5f459afb804ea01734 100644 (file)
--- a/src/libsystemd-bus/bus-socket.c
+++ b/src/libsystemd-bus/bus-socket.c
@@ -313,13 +313,16 @@ static int bus_socket_auth_verify_server(sd_bus *b) {
 
         assert(b);
 
-        if (b->rbuffer_size < 3)
+        if (b->rbuffer_size < 1)
                 return 0;
 
         /* First char must be a NUL byte */
         if (*(char*) b->rbuffer != 0)
                 return -EIO;
 
+        if (b->rbuffer_size < 3)
+                return 0;
+
         /* Begin with the first line */
         if (b->auth_rbegin <= 0)
                 b->auth_rbegin = 1;