From 06fc3b0d2251b550f530a1c42e0f9c5d022476dd Mon Sep 17 00:00:00 2001 From: Alexander Gordeev Date: Fri, 1 Sep 2023 08:11:14 +0200 Subject: [PATCH] s390/vmem: do not silently ignore mapping limit The only interface that allows drivers establishing liner mappings is vmem_add_mapping(). It does check a requested range against allowed limits and a call to modify_pagetable() with an invalid mapping range is impossible. Hence, an attempt to map an address range outside of the identity mapping or vmemmap array could only be kernel bug. Reviewed-by: Heiko Carstens Signed-off-by: Alexander Gordeev Signed-off-by: Heiko Carstens --- arch/s390/mm/vmem.c | 18 +++--------------- 1 file changed, 3 insertions(+), 15 deletions(-) diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c index d734058..6957d2e 100644 --- a/arch/s390/mm/vmem.c +++ b/arch/s390/mm/vmem.c @@ -290,14 +290,9 @@ out: static void try_free_pmd_table(pud_t *pud, unsigned long start) { - const unsigned long end = start + PUD_SIZE; pmd_t *pmd; int i; - /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */ - if (end > VMALLOC_START) - return; - pmd = pmd_offset(pud, start); for (i = 0; i < PTRS_PER_PMD; i++, pmd++) if (!pmd_none(*pmd)) @@ -362,14 +357,9 @@ out: static void try_free_pud_table(p4d_t *p4d, unsigned long start) { - const unsigned long end = start + P4D_SIZE; pud_t *pud; int i; - /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */ - if (end > VMALLOC_START) - return; - pud = pud_offset(p4d, start); for (i = 0; i < PTRS_PER_PUD; i++, pud++) { if (!pud_none(*pud)) @@ -412,14 +402,9 @@ out: static void try_free_p4d_table(pgd_t *pgd, unsigned long start) { - const unsigned long end = start + PGDIR_SIZE; p4d_t *p4d; int i; - /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */ - if (end > VMALLOC_START) - return; - p4d = p4d_offset(pgd, start); for (i = 0; i < PTRS_PER_P4D; i++, p4d++) { if (!p4d_none(*p4d)) @@ -439,6 +424,9 @@ static int modify_pagetable(unsigned long start, unsigned long end, bool add, if (WARN_ON_ONCE(!PAGE_ALIGNED(start | end))) return -EINVAL; + /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */ + if (WARN_ON_ONCE(end > VMALLOC_START)) + return -EINVAL; for (addr = start; addr < end; addr = next) { next = pgd_addr_end(addr, end); pgd = pgd_offset_k(addr); -- 2.7.4