[PATCH AUTOSEL 5.14 42/47] s390/kasan: fix large PMD pages address alignment check

Sasha Levin
2021-09-06T01:22:27Z

From: Alexander Gordeev <agordeev@linux.ibm.com>

[ Upstream commit ddd63c85ef67ea9ea7282ad35eafb6568047126e ]

It is currently possible to initialize a large PMD page when
the address is not aligned on page boundary.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/mm/kasan_init.c | 41 +++++++++++++++++++--------------------
1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/arch/s390/mm/kasan_init.c b/arch/s390/mm/kasan_init.c
index a0fdc6dc5f9d..cc3af046c14e 100644
--- a/arch/s390/mm/kasan_init.c
+++ b/arch/s390/mm/kasan_init.c
@@ -107,6 +107,9 @@ static void __init kasan_early_pgtable_populate(unsigned long address,
sgt_prot &= ~_SEGMENT_ENTRY_NOEXEC;
}

+ /*
+ * The first 1MB of 1:1 mapping is mapped with 4KB pages
+ */
while (address < end) {
pg_dir = pgd_offset_k(address);
if (pgd_none(*pg_dir)) {
@@ -157,30 +160,26 @@ static void __init kasan_early_pgtable_populate(unsigned long address,

pm_dir = pmd_offset(pu_dir, address);
if (pmd_none(*pm_dir)) {
- if (mode == POPULATE_ZERO_SHADOW &&
- IS_ALIGNED(address, PMD_SIZE) &&
+ if (IS_ALIGNED(address, PMD_SIZE) &&
end - address >= PMD_SIZE) {
- pmd_populate(&init_mm, pm_dir,
- kasan_early_shadow_pte);
- address = (address + PMD_SIZE) & PMD_MASK;
- continue;
- }
- /* the first megabyte of 1:1 is mapped with 4k pages */
- if (has_edat && address && end - address >= PMD_SIZE &&
- mode != POPULATE_ZERO_SHADOW) {
- void *page;
-
- if (mode == POPULATE_ONE2ONE) {
- page = (void *)address;
- } else {
- page = kasan_early_alloc_segment();
- memset(page, 0, _SEGMENT_SIZE);
+ if (mode == POPULATE_ZERO_SHADOW) {
+ pmd_populate(&init_mm, pm_dir, kasan_early_shadow_pte);
+ address = (address + PMD_SIZE) & PMD_MASK;
+ continue;
+ } else if (has_edat && address) {
+ void *page;
+
+ if (mode == POPULATE_ONE2ONE) {
+ page = (void *)address;
+ } else {
+ page = kasan_early_alloc_segment();
+ memset(page, 0, _SEGMENT_SIZE);
+ }
+ pmd_val(*pm_dir) = __pa(page) | sgt_prot;
+ address = (address + PMD_SIZE) & PMD_MASK;
+ continue;
}
- pmd_val(*pm_dir) = __pa(page) | sgt_prot;
- address = (address + PMD_SIZE) & PMD_MASK;
- continue;
}
-
pt_dir = kasan_early_pte_alloc();
pmd_populate(&init_mm, pm_dir, pt_dir);
} else if (pmd_large(*pm_dir)) {
--
2.30.2