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/skbuff.h | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 include/kunit/skbuff.h (limited to 'include/kunit/skbuff.h') diff --git a/include/kunit/skbuff.h b/include/kunit/skbuff.h new file mode 100644 index 000000000..077846943 --- /dev/null +++ b/include/kunit/skbuff.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * KUnit resource management helpers for SKBs (skbuff). + * + * Copyright (C) 2023 Intel Corporation + */ + +#ifndef _KUNIT_SKBUFF_H +#define _KUNIT_SKBUFF_H + +#include +#include + +static void kunit_action_kfree_skb(void *p) +{ + kfree_skb((struct sk_buff *)p); +} + +/** + * kunit_zalloc_skb() - Allocate and initialize a resource managed skb. + * @test: The test case to which the skb belongs + * @len: size to allocate + * @gfp: allocation flags + * + * Allocate a new struct sk_buff with gfp flags, zero fill the given length + * and add it as a resource to the kunit test for automatic cleanup. + * + * Returns: newly allocated SKB, or %NULL on error + */ +static inline struct sk_buff *kunit_zalloc_skb(struct kunit *test, int len, + gfp_t gfp) +{ + struct sk_buff *res = alloc_skb(len, gfp); + + if (!res || skb_pad(res, len)) + return NULL; + + if (kunit_add_action_or_reset(test, kunit_action_kfree_skb, res)) + return NULL; + + return res; +} + +/** + * kunit_kfree_skb() - Like kfree_skb except for allocations managed by KUnit. + * @test: The test case to which the resource belongs. + * @skb: The SKB to free. + */ +static inline void kunit_kfree_skb(struct kunit *test, struct sk_buff *skb) +{ + if (!skb) + return; + + kunit_release_action(test, kunit_action_kfree_skb, (void *)skb); +} + +#endif /* _KUNIT_SKBUFF_H */ -- cgit v1.3.1