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/aligned_data.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 include/net/aligned_data.h (limited to 'include/net/aligned_data.h') diff --git a/include/net/aligned_data.h b/include/net/aligned_data.h new file mode 100644 index 000000000..e1a1c8aed --- /dev/null +++ b/include/net/aligned_data.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef _NET_ALIGNED_DATA_H +#define _NET_ALIGNED_DATA_H + +#include +#include + +/* Structure holding cacheline aligned fields on SMP builds. + * Each field or group should have an ____cacheline_aligned_in_smp + * attribute to ensure no accidental false sharing can happen. + */ +struct net_aligned_data { + atomic64_t net_cookie ____cacheline_aligned_in_smp; +#if defined(CONFIG_INET) + atomic_long_t tcp_memory_allocated ____cacheline_aligned_in_smp; + atomic_long_t udp_memory_allocated ____cacheline_aligned_in_smp; +#endif +}; + +extern struct net_aligned_data net_aligned_data; + +#endif /* _NET_ALIGNED_DATA_H */ -- cgit v1.3.1