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/kunit/test-bug.h | 97 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100644 include/kunit/test-bug.h (limited to 'include/kunit/test-bug.h') diff --git a/include/kunit/test-bug.h b/include/kunit/test-bug.h new file mode 100644 index 000000000..99869029f --- /dev/null +++ b/include/kunit/test-bug.h @@ -0,0 +1,97 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * KUnit API providing hooks for non-test code to interact with tests. + * + * Copyright (C) 2020, Google LLC. + * Author: Uriel Guajardo + */ + +#ifndef _KUNIT_TEST_BUG_H +#define _KUNIT_TEST_BUG_H + +#include /* for NULL */ +#include /* for bool */ + +#if IS_ENABLED(CONFIG_KUNIT) + +#include /* For static branch */ +#include + +/* Static key if KUnit is running any tests. */ +DECLARE_STATIC_KEY_FALSE(kunit_running); + +/* Hooks table: a table of function pointers filled in when kunit loads */ +extern struct kunit_hooks_table { + __printf(3, 4) void (*fail_current_test)(const char*, int, const char*, ...); + void *(*get_static_stub_address)(struct kunit *test, void *real_fn_addr); + bool (*is_suppressed_warning)(bool count); +} kunit_hooks; + +/** + * kunit_get_current_test() - Return a pointer to the currently running + * KUnit test. + * + * If a KUnit test is running in the current task, returns a pointer to its + * associated struct kunit. This pointer can then be passed to any KUnit + * function or assertion. If no test is running (or a test is running in a + * different task), returns NULL. + * + * This function is safe to call even when KUnit is disabled. If CONFIG_KUNIT + * is not enabled, it will compile down to nothing and will return quickly no + * test is running. + */ +static inline struct kunit *kunit_get_current_test(void) +{ + if (!static_branch_unlikely(&kunit_running)) + return NULL; + + return current->kunit_test; +} + + +/** + * kunit_fail_current_test() - If a KUnit test is running, fail it. + * + * If a KUnit test is running in the current task, mark that test as failed. + */ +#define kunit_fail_current_test(fmt, ...) do { \ + if (static_branch_unlikely(&kunit_running)) { \ + /* Guaranteed to be non-NULL when kunit_running true*/ \ + kunit_hooks.fail_current_test(__FILE__, __LINE__, \ + fmt, ##__VA_ARGS__); \ + } \ + } while (0) + +/** + * kunit_is_suppressed_warning() - Check if warnings are being suppressed + * by the current KUnit test. + * @count: if true, increment the suppression counter on match. + * + * Returns true if the current task has active warning suppression. + * Uses the kunit_running static branch for zero overhead when no tests run. + * + * A single WARN*() may traverse multiple call sites in the warning path + * (e.g., __warn_printk() and __report_bug()). Pass @count = true at the + * primary suppression point to count each warning exactly once, and + * @count = false at secondary points to suppress output without + * inflating the count. + */ +static inline bool kunit_is_suppressed_warning(bool count) +{ + if (!static_branch_unlikely(&kunit_running)) + return false; + + return kunit_hooks.is_suppressed_warning && + kunit_hooks.is_suppressed_warning(count); +} + +#else + +static inline struct kunit *kunit_get_current_test(void) { return NULL; } +static inline bool kunit_is_suppressed_warning(bool count) { return false; } + +#define kunit_fail_current_test(fmt, ...) do {} while (0) + +#endif + +#endif /* _KUNIT_TEST_BUG_H */ -- cgit v1.3.1