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 --- arch/powerpc/sysdev/dcr.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 arch/powerpc/sysdev/dcr.c (limited to 'arch/powerpc/sysdev/dcr.c') diff --git a/arch/powerpc/sysdev/dcr.c b/arch/powerpc/sysdev/dcr.c new file mode 100644 index 000000000..cb44a6995 --- /dev/null +++ b/arch/powerpc/sysdev/dcr.c @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp. + * + */ + +#undef DEBUG + +#include +#include +#include +#include + +unsigned int dcr_resource_start(const struct device_node *np, + unsigned int index) +{ + unsigned int ds; + const u32 *dr = of_get_property(np, "dcr-reg", &ds); + + if (dr == NULL || ds & 1 || index >= (ds / 8)) + return 0; + + return dr[index * 2]; +} +EXPORT_SYMBOL_GPL(dcr_resource_start); + +unsigned int dcr_resource_len(const struct device_node *np, unsigned int index) +{ + unsigned int ds; + const u32 *dr = of_get_property(np, "dcr-reg", &ds); + + if (dr == NULL || ds & 1 || index >= (ds / 8)) + return 0; + + return dr[index * 2 + 1]; +} +EXPORT_SYMBOL_GPL(dcr_resource_len); + +DEFINE_SPINLOCK(dcr_ind_lock); +EXPORT_SYMBOL_GPL(dcr_ind_lock); -- cgit v1.3.1