From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- init/noinitramfs.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 init/noinitramfs.c (limited to 'init/noinitramfs.c') diff --git a/init/noinitramfs.c b/init/noinitramfs.c new file mode 100644 index 000000000..d1d26b93d --- /dev/null +++ b/init/noinitramfs.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * init/noinitramfs.c + * + * Copyright (C) 2006, NXP Semiconductors, All Rights Reserved + * Author: Jean-Paul Saman + */ +#include +#include +#include +#include +#include +#include + +/* + * Create a simple rootfs that is similar to the default initramfs + */ +static int __init default_rootfs(void) +{ + int err; + + usermodehelper_enable(); + err = init_mkdir("/dev", 0755); + if (err < 0) + goto out; + + err = init_mknod("/dev/console", S_IFCHR | S_IRUSR | S_IWUSR, + new_encode_dev(MKDEV(5, 1))); + if (err < 0) + goto out; + + err = init_mkdir("/root", 0700); + if (err < 0) + goto out; + + return 0; + +out: + printk(KERN_WARNING "Failed to create a rootfs\n"); + return err; +} +rootfs_initcall(default_rootfs); -- cgit v1.3.1