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/asm-generic/bitops/ext2-atomic.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) create mode 100644 include/asm-generic/bitops/ext2-atomic.h (limited to 'include/asm-generic/bitops/ext2-atomic.h') diff --git a/include/asm-generic/bitops/ext2-atomic.h b/include/asm-generic/bitops/ext2-atomic.h new file mode 100644 index 000000000..0cfc3180b --- /dev/null +++ b/include/asm-generic/bitops/ext2-atomic.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_GENERIC_BITOPS_EXT2_ATOMIC_H_ +#define _ASM_GENERIC_BITOPS_EXT2_ATOMIC_H_ + +/* + * Spinlock based version of ext2 atomic bitops + */ + +#define ext2_set_bit_atomic(lock, nr, addr) \ + ({ \ + int ret; \ + spin_lock(lock); \ + ret = __test_and_set_bit_le(nr, addr); \ + spin_unlock(lock); \ + ret; \ + }) + +#define ext2_clear_bit_atomic(lock, nr, addr) \ + ({ \ + int ret; \ + spin_lock(lock); \ + ret = __test_and_clear_bit_le(nr, addr); \ + spin_unlock(lock); \ + ret; \ + }) + +#endif /* _ASM_GENERIC_BITOPS_EXT2_ATOMIC_H_ */ -- cgit v1.3.1