fork: allow CLONE_NEWTIME in clone3 flags

commit a402f1e35313fc7ce2ca60f543c4402c2c7c3544 upstream.

Currently, calling clone3() with CLONE_NEWTIME in clone_args->flags
fails with -EINVAL. This is because CLONE_NEWTIME intersects with
CSIGNAL. However, CSIGNAL was deprecated when clone3 was introduced in
commit 7f192e3cd316 ("fork: add clone3"), allowing re-use of that part
of clone flags.

Fix this by explicitly allowing CLONE_NEWTIME in clone3_args_valid. This
is also in line with the respective check in check_unshare_flags which
allow CLONE_NEWTIME for unshare().

Fixes: 769071ac9f20 ("ns: Introduce Time Namespace")
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/fork.c b/kernel/fork.c
index 3fb7e9e6a7b9785da00699f4aedbcfac395ad86e..68eab6ce30859aa14a4f7cbbdb9e2633456a1e25 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2829,7 +2829,7 @@ static bool clone3_args_valid(struct kernel_clone_args *kargs)
         * - make the CLONE_DETACHED bit reusable for clone3
         * - make the CSIGNAL bits reusable for clone3
         */
-       if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
+       if (kargs->flags & (CLONE_DETACHED | (CSIGNAL & (~CLONE_NEWTIME))))
                return false;
 
        if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==