From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Mon, 19 Dec 2022 13:36:08 +0000 (+0100)
Subject: sd-event: never pass negative errnos as signalfd to signalfd
X-Git-Tag: v253-rc1~241^2~4
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=cbff793ffb280d9d11e5d7b1dc3964276491bee8;p=thirdparty%2Fsystemd.git

sd-event: never pass negative errnos as signalfd to signalfd

We treat any negative value as "invalid fd", but signalfd only
accepts -1.
---

diff --git a/src/libsystemd/sd-event/sd-event.c b/src/libsystemd/sd-event/sd-event.c
index 299a6a2c8ce..c936fcb3b64 100644
--- a/src/libsystemd/sd-event/sd-event.c
+++ b/src/libsystemd/sd-event/sd-event.c
@@ -659,7 +659,9 @@ static int event_make_signal_data(
         ss_copy = d->sigset;
         assert_se(sigaddset(&ss_copy, sig) >= 0);
 
-        r = signalfd(d->fd, &ss_copy, SFD_NONBLOCK|SFD_CLOEXEC);
+        r = signalfd(d->fd >= 0 ? d->fd : -1,   /* the first arg must be -1 or a valid signalfd */
+                     &ss_copy,
+                     SFD_NONBLOCK|SFD_CLOEXEC);
         if (r < 0) {
                 r = -errno;
                 goto fail;