From e82a118f57b89bbb437ce70780fc2678d5c281e5 Mon Sep 17 00:00:00 2001 From: Eugene Syromiatnikov Date: Sun, 12 Apr 2020 22:25:33 +0200 Subject: [PATCH] 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: ef2c41cf38a7559b ("clone3: allow spawning processes into cgroups") Signed-off-by: Eugene Syromiatnikov Acked-by: Christian Brauner Link: https://lore.kernel.org/r/20200412202533.GA29554@asgard.redhat.com Signed-off-by: Christian Brauner --- kernel/fork.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/fork.c b/kernel/fork.c index 4385f3d639f2..b4f7775623c8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -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){