On Tue, Feb 18, 2020 at 09:47:59AM +0300, Dan Carpenter wrote: > Hello Christian Brauner, > > The patch ef2c41cf38a7: "clone3: allow spawning processes into > cgroups" from Feb 5, 2020, leads to the following static checker > warning: > > kernel/fork.c:2632 copy_clone_args_from_user() > warn: unsigned 'args.cgroup' is never less than zero. Thanks, good catch. This strikes me as a great patch for the linux-kernel-mentees project so I've Cced the list. I'll wait for about two weeks for a patch and if none has surfaced by then I'll fix it myself. For anyone wanting to fix this, please note that this patch sits in Tejun's cgroup tree, i.e. your fix needs to be made against the following tree: https://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git/log/?h=for-5.7 Thanks! Christian > > kernel/fork.c > 2598 noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, > 2599 struct clone_args __user *uargs, > 2600 size_t usize) > 2601 { > 2602 int err; > 2603 struct clone_args args; > 2604 pid_t *kset_tid = kargs->set_tid; > 2605 > 2606 if (unlikely(usize > PAGE_SIZE)) > 2607 return -E2BIG; > 2608 if (unlikely(usize < CLONE_ARGS_SIZE_VER0)) > 2609 return -EINVAL; > 2610 > 2611 err = copy_struct_from_user(&args, sizeof(args), uargs, usize); > 2612 if (err) > 2613 return err; > 2614 > 2615 if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL)) > 2616 return -EINVAL; > 2617 > 2618 if (unlikely(!args.set_tid && args.set_tid_size > 0)) > 2619 return -EINVAL; > 2620 > 2621 if (unlikely(args.set_tid && args.set_tid_size == 0)) > 2622 return -EINVAL; > 2623 > 2624 /* > 2625 * Verify that higher 32bits of exit_signal are unset and that > 2626 * it is a valid signal > 2627 */ > 2628 if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) || > 2629 !valid_signal(args.exit_signal))) > 2630 return -EINVAL; > 2631 > 2632 if ((args.flags & CLONE_INTO_CGROUP) && args.cgroup < 0) > ^^^^^^^^^^^^^^^ > This is a u64 so it can't be negative. I'm not sure what was intended. > > 2633 return -EINVAL; > 2634 > > regards, > dan carpenter
