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/trace/events/rseq.h | 62 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 include/trace/events/rseq.h (limited to 'include/trace/events/rseq.h') diff --git a/include/trace/events/rseq.h b/include/trace/events/rseq.h new file mode 100644 index 000000000..ce85d650b --- /dev/null +++ b/include/trace/events/rseq.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM rseq + +#if !defined(_TRACE_RSEQ_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_RSEQ_H + +#include +#include + +TRACE_EVENT(rseq_update, + + TP_PROTO(struct task_struct *t), + + TP_ARGS(t), + + TP_STRUCT__entry( + __field(s32, cpu_id) + __field(s32, node_id) + __field(s32, mm_cid) + ), + + TP_fast_assign( + __entry->cpu_id = t->rseq.ids.cpu_id; + __entry->node_id = cpu_to_node(__entry->cpu_id); + __entry->mm_cid = t->rseq.ids.mm_cid; + ), + + TP_printk("cpu_id=%d node_id=%d mm_cid=%d", __entry->cpu_id, + __entry->node_id, __entry->mm_cid) +); + +TRACE_EVENT(rseq_ip_fixup, + + TP_PROTO(unsigned long regs_ip, unsigned long start_ip, + unsigned long post_commit_offset, unsigned long abort_ip), + + TP_ARGS(regs_ip, start_ip, post_commit_offset, abort_ip), + + TP_STRUCT__entry( + __field(unsigned long, regs_ip) + __field(unsigned long, start_ip) + __field(unsigned long, post_commit_offset) + __field(unsigned long, abort_ip) + ), + + TP_fast_assign( + __entry->regs_ip = regs_ip; + __entry->start_ip = start_ip; + __entry->post_commit_offset = post_commit_offset; + __entry->abort_ip = abort_ip; + ), + + TP_printk("regs_ip=0x%lx start_ip=0x%lx post_commit_offset=%lu abort_ip=0x%lx", + __entry->regs_ip, __entry->start_ip, + __entry->post_commit_offset, __entry->abort_ip) +); + +#endif /* _TRACE_SOCK_H */ + +/* This part must be outside protection */ +#include -- cgit v1.3.1