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/mm/pgtable-64.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) create mode 100644 arch/mips/mm/pgtable-64.c (limited to 'arch/mips/mm/pgtable-64.c') diff --git a/arch/mips/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c new file mode 100644 index 000000000..b24f865de --- /dev/null +++ b/arch/mips/mm/pgtable-64.c @@ -0,0 +1,119 @@ +/* + * 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) 1999, 2000 by Silicon Graphics + * Copyright (C) 2003 by Ralf Baechle + */ +#include +#include +#include +#include +#include +#include + +void pgd_init(void *addr) +{ + unsigned long *p, *end; + unsigned long entry; + +#if !defined(__PAGETABLE_PUD_FOLDED) + entry = (unsigned long)invalid_pud_table; +#elif !defined(__PAGETABLE_PMD_FOLDED) + entry = (unsigned long)invalid_pmd_table; +#else + entry = (unsigned long)invalid_pte_table; +#endif + + p = (unsigned long *) addr; + end = p + PTRS_PER_PGD; + + do { + p[0] = entry; + p[1] = entry; + p[2] = entry; + p[3] = entry; + p[4] = entry; + p += 8; + p[-3] = entry; + p[-2] = entry; + p[-1] = entry; + } while (p != end); +} + +#ifndef __PAGETABLE_PMD_FOLDED +void pmd_init(void *addr) +{ + unsigned long *p, *end; + unsigned long pagetable = (unsigned long)invalid_pte_table; + + p = (unsigned long *)addr; + end = p + PTRS_PER_PMD; + + do { + p[0] = pagetable; + p[1] = pagetable; + p[2] = pagetable; + p[3] = pagetable; + p[4] = pagetable; + p += 8; + p[-3] = pagetable; + p[-2] = pagetable; + p[-1] = pagetable; + } while (p != end); +} +EXPORT_SYMBOL_GPL(pmd_init); +#endif + +#ifndef __PAGETABLE_PUD_FOLDED +void pud_init(void *addr) +{ + unsigned long *p, *end; + unsigned long pagetable = (unsigned long)invalid_pmd_table; + + p = (unsigned long *)addr; + end = p + PTRS_PER_PUD; + + do { + p[0] = pagetable; + p[1] = pagetable; + p[2] = pagetable; + p[3] = pagetable; + p[4] = pagetable; + p += 8; + p[-3] = pagetable; + p[-2] = pagetable; + p[-1] = pagetable; + } while (p != end); +} +#endif + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +void set_pmd_at(struct mm_struct *mm, unsigned long addr, + pmd_t *pmdp, pmd_t pmd) +{ + *pmdp = pmd; +} +#endif + +void __init pagetable_init(void) +{ + unsigned long vaddr; + pgd_t *pgd_base; + + /* Initialize the entire pgd. */ + pgd_init(swapper_pg_dir); +#ifndef __PAGETABLE_PUD_FOLDED + pud_init(invalid_pud_table); +#endif +#ifndef __PAGETABLE_PMD_FOLDED + pmd_init(invalid_pmd_table); +#endif + pgd_base = swapper_pg_dir; + /* + * Fixed mappings: + */ + vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK; + fixrange_init(vaddr, vaddr + FIXADDR_SIZE, pgd_base); +} -- cgit v1.3.1