silence warning about failed unmounting of /sys (overlay options)

1 files changed, 5 insertions, 2 deletions

diff --git a/src/firejail/fs.c b/src/firejail/fs.c
index 98efb5e41..08b268d93 100644
--- a/src/firejail/fs.c
+++ b/src/firejail/fs.c
@@ -571,8 +571,11 @@ void fs_proc_sys_dev_boot(void) {
         /* Mount a version of /sys that describes the network namespace */
         if (arg_debug)
                 printf("Remounting /sys directory\n");
-        if (umount2("/sys", MNT_DETACH) < 0)
-                fwarning("failed to unmount /sys\n");
+        // if this is an overlay, just mount a new /sys on top of the upper layer
+        if (!arg_overlay) {
+                if (umount2("/sys", MNT_DETACH) < 0)
+                        fwarning("failed to unmount /sys\n");
+        }
         if (mount("sysfs", "/sys", "sysfs", MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REC, NULL) < 0)
                 fwarning("failed to mount /sys\n");
         else