[systemd-devel] [PATCH] libudev-monitor: ensure proper string termination

[Topi Miettinen]

Leave space for the terminating zero when reading and make sure
that the last byte is zero. This also makes the check for long packets
equivalent to code before 9c89c1ca: reject also packets with size 8192.
---
 src/libudev/libudev-monitor.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c
index 4cfb2f6..b7fc031 100644
--- a/src/libudev/libudev-monitor.c
+++ b/src/libudev/libudev-monitor.c
@@ -590,7 +590,7 @@ retry:
         if (udev_monitor == NULL)
                 return NULL;
         iov.iov_base = &buf;
-        iov.iov_len = sizeof(buf);
+        iov.iov_len = sizeof(buf) - 1; /* Leave space for terminating zero */
         memzero(&smsg, sizeof(struct msghdr));
         smsg.msg_iov = &iov;
         smsg.msg_iovlen = 1;
@@ -642,6 +642,8 @@ retry:
         if (udev_device == NULL)
                 return NULL;
 
+        buf.raw[sizeof(buf.raw) - 1] = '\0';
+
         if (memcmp(buf.raw, "libudev", 8) == 0) {
                 /* udev message needs proper version magic */
                 if (buf.nlh.magic != htonl(UDEV_MONITOR_MAGIC)) {
-- 
2.1.4