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 --- tools/include/nolibc/assert.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 tools/include/nolibc/assert.h (limited to 'tools/include/nolibc/assert.h') diff --git a/tools/include/nolibc/assert.h b/tools/include/nolibc/assert.h new file mode 100644 index 000000000..84ff8ad9a --- /dev/null +++ b/tools/include/nolibc/assert.h @@ -0,0 +1,36 @@ +/* SPDX-License-Identifier: LGPL-2.1 OR MIT */ +/* + * Assert for NOLIBC + * Copyright (C) 2026 Thomas Weißschuh + */ + +/* make sure to include all global symbols */ +#include "nolibc.h" + +#ifndef _NOLIBC_ASSERT_H +#define _NOLIBC_ASSERT_H + +#include "errno.h" +#include "stdio.h" +#include "stdlib.h" + +#endif /* _NOLIBC_ASSERT_H */ + +/* NDEBUG needs to be evaluated on *each* inclusion */ +#ifdef assert +#undef assert +#endif + +#ifndef NDEBUG +#define assert(expr) \ +({ \ + if (!(expr)) { \ + fprintf(stderr, "%s: %s:%d: %s: Assertion `%s' failed.\n", \ + program_invocation_short_name, __FILE__, __LINE__, __func__, \ + #expr); \ + abort(); \ + } \ +}) +#else +#define assert(expr) ((void)0) +#endif -- cgit v1.3.1