Commit e82a118f authored Apr 12, 2020 by Eugene Syromiatnikov Committed by Christian Brauner Apr 15, 2020

clone3: fix cgroup argument sanity check

Checking that cgroup field value of struct clone_args is less than 0
is useless, as it is defined as unsigned 64-bit integer. Moreover,
it doesn't catch the situations where its higher bits are lost during
the assignment to the cgroup field of the cgroup field of the internal
struct kernel_clone_args (where it is declared as signed 32-bit
integer), so it is still possible to pass garbage there. A check
against INT_MAX solves both these issues.

Fixes: ef2c41cf ("clone3: allow spawning processes into cgroups")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20200412202533.GA29554@asgard.redhat.com

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

parent 3075afdf

kernel/fork.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2631,7 +2631,7 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
		!valid_signal(args.exit_signal)))
		return -EINVAL;

		if ((args.flags & CLONE_INTO_CGROUP) && args.cgroup < 0)
		if ((args.flags & CLONE_INTO_CGROUP) && args.cgroup > INT_MAX)
		return -EINVAL;

		*kargs = (struct kernel_clone_args){