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/mips/cavium-octeon/cpu.c | 50 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 arch/mips/cavium-octeon/cpu.c (limited to 'arch/mips/cavium-octeon/cpu.c') diff --git a/arch/mips/cavium-octeon/cpu.c b/arch/mips/cavium-octeon/cpu.c new file mode 100644 index 000000000..036d56cc4 --- /dev/null +++ b/arch/mips/cavium-octeon/cpu.c @@ -0,0 +1,50 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2009 Wind River Systems, + * written by Ralf Baechle + */ +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +static int cnmips_cu2_call(struct notifier_block *nfb, unsigned long action, + void *data) +{ + unsigned long flags; + unsigned int status; + + switch (action) { + case CU2_EXCEPTION: + prefetch(¤t->thread.cp2); + local_irq_save(flags); + KSTK_STATUS(current) |= ST0_CU2; + status = read_c0_status(); + write_c0_status(status | ST0_CU2); + octeon_cop2_restore(&(current->thread.cp2)); + write_c0_status(status & ~ST0_CU2); + local_irq_restore(flags); + + return NOTIFY_BAD; /* Don't call default notifier */ + } + + return NOTIFY_OK; /* Let default notifier send signals */ +} + +static int __init cnmips_cu2_setup(void) +{ + return cu2_notifier(cnmips_cu2_call, 0); +} +early_initcall(cnmips_cu2_setup); -- cgit v1.3.1