From 045a3d5989f7565dc496013a9e96d95d86a12cc8 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Fri, 7 Oct 2016 12:12:10 +0200 Subject: [PATCH] manager: be stricter with incomining notifications, warn properly about too large ones Let's make the kernel let us know the full, original datagram size of the incoming message. If it's larger than the buffer space provided by us, drop the whole message with a warning. Before this change the kernel would truncate the message for us to the buffer space provided, and we'd not complain about this, and simply process the incomplete message as far as it made sense. --- src/core/manager.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/core/manager.c b/src/core/manager.c index ab65d630a1..66b8904e4e 100644 --- a/src/core/manager.c +++ b/src/core/manager.c @@ -1720,7 +1720,7 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t return 0; } - n = recvmsg(m->notify_fd, &msghdr, MSG_DONTWAIT|MSG_CMSG_CLOEXEC); + n = recvmsg(m->notify_fd, &msghdr, MSG_DONTWAIT|MSG_CMSG_CLOEXEC|MSG_TRUNC); if (n < 0) { if (IN_SET(errno, EAGAIN, EINTR)) return 0; /* Spurious wakeup, try again */ @@ -1761,7 +1761,7 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t return 0; } - if ((size_t) n >= sizeof(buf)) { + if ((size_t) n >= sizeof(buf) || (msghdr.msg_flags & MSG_TRUNC)) { log_warning("Received notify message exceeded maximum size. Ignoring."); return 0; }