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 --- include/asm-generic/switch_to.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 include/asm-generic/switch_to.h (limited to 'include/asm-generic/switch_to.h') diff --git a/include/asm-generic/switch_to.h b/include/asm-generic/switch_to.h new file mode 100644 index 000000000..5897d100a --- /dev/null +++ b/include/asm-generic/switch_to.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Generic task switch macro wrapper. + * + * It should be possible to use these on really simple architectures, + * but it serves more as a starting point for new ports. + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ +#ifndef __ASM_GENERIC_SWITCH_TO_H +#define __ASM_GENERIC_SWITCH_TO_H + +#include + +/* + * Context switching is now performed out-of-line in switch_to.S + */ +extern struct task_struct *__switch_to(struct task_struct *, + struct task_struct *); + +#define switch_to(prev, next, last) \ + do { \ + ((last) = __switch_to((prev), (next))); \ + } while (0) + +#endif /* __ASM_GENERIC_SWITCH_TO_H */ -- cgit v1.3.1