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/try-catch.h | 63 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 include/kunit/try-catch.h (limited to 'include/kunit/try-catch.h') diff --git a/include/kunit/try-catch.h b/include/kunit/try-catch.h new file mode 100644 index 000000000..d4e1a5b98 --- /dev/null +++ b/include/kunit/try-catch.h @@ -0,0 +1,63 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * An API to allow a function, that may fail, to be executed, and recover in a + * controlled manner. + * + * Copyright (C) 2019, Google LLC. + * Author: Brendan Higgins + */ + +#ifndef _KUNIT_TRY_CATCH_H +#define _KUNIT_TRY_CATCH_H + +#include + +typedef void (*kunit_try_catch_func_t)(void *); + +struct kunit; + +/** + * struct kunit_try_catch - provides a generic way to run code which might fail. + * @test: The test case that is currently being executed. + * @try_result: Contains any errno obtained while running test case. + * @try: The function, the test case, to attempt to run. + * @catch: The function called if @try bails out. + * @context: used to pass user data to the try and catch functions. + * + * kunit_try_catch provides a generic, architecture independent way to execute + * an arbitrary function of type kunit_try_catch_func_t which may bail out by + * calling kunit_try_catch_throw(). If kunit_try_catch_throw() is called, @try + * is stopped at the site of invocation and @catch is called. + * + * struct kunit_try_catch provides a generic interface for the functionality + * needed to implement kunit->abort() which in turn is needed for implementing + * assertions. Assertions allow stating a precondition for a test simplifying + * how test cases are written and presented. + * + * Assertions are like expectations, except they abort (call + * kunit_try_catch_throw()) when the specified condition is not met. This is + * useful when you look at a test case as a logical statement about some piece + * of code, where assertions are the premises for the test case, and the + * conclusion is a set of predicates, rather expectations, that must all be + * true. If your premises are violated, it does not makes sense to continue. + */ +struct kunit_try_catch { + /* private: internal use only. */ + struct kunit *test; + int try_result; + kunit_try_catch_func_t try; + kunit_try_catch_func_t catch; + unsigned long timeout; + void *context; +}; + +void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context); + +void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch); + +static inline int kunit_try_catch_get_result(struct kunit_try_catch *try_catch) +{ + return try_catch->try_result; +} + +#endif /* _KUNIT_TRY_CATCH_H */ -- cgit v1.3.1