From 06fc3b0d2251b550f530a1c42e0f9c5d022476dd Mon Sep 17 00:00:00 2001
From: Alexander Gordeev <agordeev@linux.ibm.com>
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 <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
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 d734058f28d31..6957d2ed97bf0 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -290,14 +290,9 @@ static int __ref modify_pmd_table(pud_t *pud, unsigned long addr,
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 @@ static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end,
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 @@ static int modify_p4d_table(pgd_t *pgd, unsigned long addr, unsigned long end,
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);
--
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