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 --- drivers/md/bcache/debug.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 drivers/md/bcache/debug.h (limited to 'drivers/md/bcache/debug.h') diff --git a/drivers/md/bcache/debug.h b/drivers/md/bcache/debug.h new file mode 100644 index 000000000..fb3d4dff4 --- /dev/null +++ b/drivers/md/bcache/debug.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _BCACHE_DEBUG_H +#define _BCACHE_DEBUG_H + +struct bio; +struct cached_dev; +struct cache_set; + +#ifdef CONFIG_BCACHE_DEBUG + +void bch_btree_verify(struct btree *b); +void bch_data_verify(struct cached_dev *dc, struct bio *bio); + +#define expensive_debug_checks(c) ((c)->expensive_debug_checks) +#define key_merging_disabled(c) ((c)->key_merging_disabled) +#define bypass_torture_test(d) ((d)->bypass_torture_test) + +#else /* DEBUG */ + +static inline void bch_btree_verify(struct btree *b) {} +static inline void bch_data_verify(struct cached_dev *dc, struct bio *bio) {} + +#define expensive_debug_checks(c) 0 +#define key_merging_disabled(c) 0 +#define bypass_torture_test(d) 0 + +#endif + +#ifdef CONFIG_DEBUG_FS +void bch_debug_init_cache_set(struct cache_set *c); +#else +static inline void bch_debug_init_cache_set(struct cache_set *c) {} +#endif + +#endif -- cgit v1.3.1