system-linux: check for open failure

Signed-off-by: Günther Kelleter <guenther.kelleter@devolo.de>

diff --git a/system-linux.c b/system-linux.c
index 6e4a1949a11874443e05d45ebf41e916fcf23219..a0389879c4d47c7a8ec8769b362aeb2cd1acb07f 100644 (file)
--- a/system-linux.c
+++ b/system-linux.c
@@ -2489,6 +2489,8 @@ int system_update_ipv6_mtu(struct device *dev, int mtu)
                        dev->ifname);
 
        int fd = open(buf, O_RDWR);
+       if (fd < 0)
+               return ret;
 
        if (!mtu) {
                ssize_t len = read(fd, buf, sizeof(buf) - 1);