Currently this might mistake a large pte for bad, or treat it as a page table, resulting in a crash or corruption.
Signed-off-by: Nicholas Piggin <npig...@gmail.com> --- mm/memory.c | 60 +++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 44 insertions(+), 16 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 602f4283122f..3a39a47920e2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2262,13 +2262,20 @@ static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, } do { next = pmd_addr_end(addr, end); - if (create || !pmd_none_or_clear_bad(pmd)) { - err = apply_to_pte_range(mm, pmd, addr, next, fn, data, - create); - if (err) - break; + if (pmd_none(*pmd) && !create) + continue; + if (WARN_ON_ONCE(pmd_leaf(*pmd))) + return -EINVAL; + if (WARN_ON_ONCE(pmd_bad(*pmd))) { + if (!create) + continue; + pmd_clear_bad(pmd); } + err = apply_to_pte_range(mm, pmd, addr, next, fn, data, create); + if (err) + break; } while (pmd++, addr = next, addr != end); + return err; } @@ -2289,13 +2296,20 @@ static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, } do { next = pud_addr_end(addr, end); - if (create || !pud_none_or_clear_bad(pud)) { - err = apply_to_pmd_range(mm, pud, addr, next, fn, data, - create); - if (err) - break; + if (pud_none(*pud) && !create) + continue; + if (WARN_ON_ONCE(pud_leaf(*pud))) + return -EINVAL; + if (WARN_ON_ONCE(pud_bad(*pud))) { + if (!create) + continue; + pud_clear_bad(pud); } + err = apply_to_pmd_range(mm, pud, addr, next, fn, data, create); + if (err) + break; } while (pud++, addr = next, addr != end); + return err; } @@ -2316,13 +2330,20 @@ static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, } do { next = p4d_addr_end(addr, end); - if (create || !p4d_none_or_clear_bad(p4d)) { - err = apply_to_pud_range(mm, p4d, addr, next, fn, data, - create); - if (err) - break; + if (p4d_none(*p4d) && !create) + continue; + if (WARN_ON_ONCE(p4d_leaf(*p4d))) + return -EINVAL; + if (WARN_ON_ONCE(p4d_bad(*p4d))) { + if (!create) + continue; + p4d_clear_bad(p4d); } + err = apply_to_pud_range(mm, p4d, addr, next, fn, data, create); + if (err) + break; } while (p4d++, addr = next, addr != end); + return err; } @@ -2341,8 +2362,15 @@ static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr, pgd = pgd_offset(mm, addr); do { next = pgd_addr_end(addr, end); - if (!create && pgd_none_or_clear_bad(pgd)) + if (pgd_none(*pgd) && !create) continue; + if (WARN_ON_ONCE(pgd_leaf(*pgd))) + return -EINVAL; + if (WARN_ON_ONCE(pgd_bad(*pgd))) { + if (!create) + continue; + pgd_clear_bad(pgd); + } err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, create); if (err) break; -- 2.23.0