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/net/hwbm.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 include/net/hwbm.h (limited to 'include/net/hwbm.h') diff --git a/include/net/hwbm.h b/include/net/hwbm.h new file mode 100644 index 000000000..bdbe91c60 --- /dev/null +++ b/include/net/hwbm.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _HWBM_H +#define _HWBM_H + +#include + +struct hwbm_pool { + /* Capacity of the pool */ + int size; + /* Size of the buffers managed */ + int frag_size; + /* Number of buffers currently used by this pool */ + int buf_num; + /* constructor called during allocation */ + int (*construct)(struct hwbm_pool *bm_pool, void *buf); + /* protect access to the buffer counter*/ + struct mutex buf_lock; + /* private data */ + void *priv; +}; +#ifdef CONFIG_HWBM +void hwbm_buf_free(struct hwbm_pool *bm_pool, void *buf); +int hwbm_pool_refill(struct hwbm_pool *bm_pool, gfp_t gfp); +int hwbm_pool_add(struct hwbm_pool *bm_pool, unsigned int buf_num); +#else +static inline void hwbm_buf_free(struct hwbm_pool *bm_pool, void *buf) {} + +static inline int hwbm_pool_refill(struct hwbm_pool *bm_pool, gfp_t gfp) +{ return 0; } + +static inline int hwbm_pool_add(struct hwbm_pool *bm_pool, + unsigned int buf_num) +{ return 0; } +#endif /* CONFIG_HWBM */ +#endif /* _HWBM_H */ -- cgit v1.3.1