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-32.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) create mode 100644 arch/mips/mm/pgtable-32.c (limited to 'arch/mips/mm/pgtable-32.c') diff --git a/arch/mips/mm/pgtable-32.c b/arch/mips/mm/pgtable-32.c new file mode 100644 index 000000000..e2cf2166d --- /dev/null +++ b/arch/mips/mm/pgtable-32.c @@ -0,0 +1,79 @@ +/* + * 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) 2003 by Ralf Baechle + */ +#include +#include +#include +#include +#include +#include +#include + +void pgd_init(void *addr) +{ + unsigned long *p = (unsigned long *)addr; + int i; + + for (i = 0; i < USER_PTRS_PER_PGD; i+=8) { + p[i + 0] = (unsigned long) invalid_pte_table; + p[i + 1] = (unsigned long) invalid_pte_table; + p[i + 2] = (unsigned long) invalid_pte_table; + p[i + 3] = (unsigned long) invalid_pte_table; + p[i + 4] = (unsigned long) invalid_pte_table; + p[i + 5] = (unsigned long) invalid_pte_table; + p[i + 6] = (unsigned long) invalid_pte_table; + p[i + 7] = (unsigned long) invalid_pte_table; + } +} + +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) +void set_pmd_at(struct mm_struct *mm, unsigned long addr, + pmd_t *pmdp, pmd_t pmd) +{ + *pmdp = pmd; +} +#endif /* defined(CONFIG_TRANSPARENT_HUGEPAGE) */ + +void __init pagetable_init(void) +{ + unsigned long vaddr; + pgd_t *pgd_base; +#ifdef CONFIG_HIGHMEM + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; +#endif + + /* Initialize the entire pgd. */ + pgd_init(swapper_pg_dir); + pgd_init(&swapper_pg_dir[USER_PTRS_PER_PGD]); + + pgd_base = swapper_pg_dir; + + /* + * Fixed mappings: + */ + vaddr = __fix_to_virt(__end_of_fixed_addresses - 1); + fixrange_init(vaddr & PMD_MASK, vaddr + FIXADDR_SIZE, pgd_base); + +#ifdef CONFIG_HIGHMEM + /* + * Permanent kmaps: + */ + vaddr = PKMAP_BASE; + fixrange_init(vaddr & PMD_MASK, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base); + + pgd = swapper_pg_dir + pgd_index(vaddr); + p4d = p4d_offset(pgd, vaddr); + pud = pud_offset(p4d, vaddr); + pmd = pmd_offset(pud, vaddr); + pte = pte_offset_kernel(pmd, vaddr); + pkmap_page_table = pte; +#endif +} -- cgit v1.3.1