From f29eef2e9072eac6f6570ff7975680bc9caeda2f Mon Sep 17 00:00:00 2001 From: Tom Gundersen Date: Wed, 30 Aug 2017 13:09:03 +0200 Subject: [PATCH] sd-bus: socket - only transmit auxillary FDs once (#6603) If a message is too large to fit into the output buffer, it will be transmitted to the kernel in several chunks. However, the FDs must only ever be transmitted once or they will bereceived by the remote end repeatedly. The D-Bus specification disallows several sets of FDs attached to one message, however, the reference implementation of D-Bus will not reject such a message, rather it will reassign the duplicate FDs to subsequent FD-carrying messages. This attaches the FD array only to the first byte of the message. --- src/libsystemd/sd-bus/bus-socket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/libsystemd/sd-bus/bus-socket.c b/src/libsystemd/sd-bus/bus-socket.c index be12516663..982af68c01 100644 --- a/src/libsystemd/sd-bus/bus-socket.c +++ b/src/libsystemd/sd-bus/bus-socket.c @@ -799,7 +799,7 @@ int bus_socket_write_message(sd_bus *bus, sd_bus_message *m, size_t *idx) { .msg_iovlen = m->n_iovec, }; - if (m->n_fds > 0) { + if (m->n_fds > 0 && *idx == 0) { struct cmsghdr *control; mh.msg_control = control = alloca(CMSG_SPACE(sizeof(int) * m->n_fds));