linux-kernel - [PATCH AUTOSEL 5.4 29/30] s390/kasan: fix large PMD pages address alignment check

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Message-Id: <20210906012244.930338-29-sashal@kernel.org>
Date:   Sun,  5 Sep 2021 21:22:42 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Alexander Gordeev <agordeev@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Sasha Levin <sashal@...nel.org>, kasan-dev@...glegroups.com,
        linux-s390@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 29/30] s390/kasan: fix large PMD pages address alignment check

From: Alexander Gordeev <agordeev@...ux.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@...ux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@...ux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@...ux.ibm.com>
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Sasha Levin <sashal@...nel.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 460f25572940..5182e0836ca7 100644
--- a/arch/s390/mm/kasan_init.c
+++ b/arch/s390/mm/kasan_init.c
@@ -101,6 +101,9 @@ static void __init kasan_early_vmemmap_populate(unsigned long address,
 	pgt_prot = pgprot_val(PAGE_KERNEL_EXEC);
 	sgt_prot = pgprot_val(SEGMENT_KERNEL_EXEC);
 
+	/*
+	 * 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)) {
@@ -146,30 +149,26 @@ static void __init kasan_early_vmemmap_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