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From: Lecopzer Chen <lecopzer@gmail.com>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	kasan-dev@googlegroups.com
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>,
	glider@google.com, yj.chiang@mediatek.com,
	Lecopzer Chen <lecopzer@gmail.com>,
	linux-mediatek@lists.infradead.org, aryabinin@virtuozzo.com,
	dan.j.williams@intel.com, akpm@linux-foundation.org,
	dvyukov@google.com
Subject: [PATCH] kasan: fix unaligned address is unhandled in kasan_remove_zero_shadow
Date: Sun,  3 Jan 2021 21:56:21 +0800	[thread overview]
Message-ID: <20210103135621.83129-1-lecopzer@gmail.com> (raw)

During testing kasan_populate_early_shadow and kasan_remove_zero_shadow,
if the shadow start and end address in kasan_remove_zero_shadow() is
not aligned to PMD_SIZE, the remain unaligned PTE won't be removed.

In the test case for kasan_remove_zero_shadow():
    shadow_start: 0xffffffb802000000, shadow end: 0xffffffbfbe000000
    3-level page table:
      PUD_SIZE: 0x40000000 PMD_SIZE: 0x200000 PAGE_SIZE: 4K
0xffffffbf80000000 ~ 0xffffffbfbdf80000 will not be removed because
in kasan_remove_pud_table(), kasan_pmd_table(*pud) is true but the
next address is 0xffffffbfbdf80000 which is not aligned to PUD_SIZE.

In the correct condition, this should fallback to the next level
kasan_remove_pmd_table() but the condition flow always continue to skip
the unaligned part.

Fix by correcting the condition when next and addr are neither aligned.

Fixes: 0207df4fa1a86 ("kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN")
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
---
 mm/kasan/init.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index 67051cfae41c..ae9158f7501f 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -372,9 +372,10 @@ static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
 
 		if (kasan_pte_table(*pmd)) {
 			if (IS_ALIGNED(addr, PMD_SIZE) &&
-			    IS_ALIGNED(next, PMD_SIZE))
+			    IS_ALIGNED(next, PMD_SIZE)) {
 				pmd_clear(pmd);
-			continue;
+				continue;
+			}
 		}
 		pte = pte_offset_kernel(pmd, addr);
 		kasan_remove_pte_table(pte, addr, next);
@@ -397,9 +398,10 @@ static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
 
 		if (kasan_pmd_table(*pud)) {
 			if (IS_ALIGNED(addr, PUD_SIZE) &&
-			    IS_ALIGNED(next, PUD_SIZE))
+			    IS_ALIGNED(next, PUD_SIZE)) {
 				pud_clear(pud);
-			continue;
+				continue;
+			}
 		}
 		pmd = pmd_offset(pud, addr);
 		pmd_base = pmd_offset(pud, 0);
@@ -423,9 +425,10 @@ static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
 
 		if (kasan_pud_table(*p4d)) {
 			if (IS_ALIGNED(addr, P4D_SIZE) &&
-			    IS_ALIGNED(next, P4D_SIZE))
+			    IS_ALIGNED(next, P4D_SIZE)) {
 				p4d_clear(p4d);
-			continue;
+				continue;
+			}
 		}
 		pud = pud_offset(p4d, addr);
 		kasan_remove_pud_table(pud, addr, next);
@@ -456,9 +459,10 @@ void kasan_remove_zero_shadow(void *start, unsigned long size)
 
 		if (kasan_p4d_table(*pgd)) {
 			if (IS_ALIGNED(addr, PGDIR_SIZE) &&
-			    IS_ALIGNED(next, PGDIR_SIZE))
+			    IS_ALIGNED(next, PGDIR_SIZE)) {
 				pgd_clear(pgd);
-			continue;
+				continue;
+			}
 		}
 
 		p4d = p4d_offset(pgd, addr);
-- 
2.25.1


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WARNING: multiple messages have this Message-ID (diff)
From: Lecopzer Chen <lecopzer@gmail.com>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	kasan-dev@googlegroups.com
Cc: dan.j.williams@intel.com, aryabinin@virtuozzo.com,
	glider@google.com, dvyukov@google.com, akpm@linux-foundation.org,
	linux-mediatek@lists.infradead.org, yj.chiang@mediatek.com,
	Lecopzer Chen <lecopzer@gmail.com>,
	Lecopzer Chen <lecopzer.chen@mediatek.com>
Subject: [PATCH] kasan: fix unaligned address is unhandled in kasan_remove_zero_shadow
Date: Sun,  3 Jan 2021 21:56:21 +0800	[thread overview]
Message-ID: <20210103135621.83129-1-lecopzer@gmail.com> (raw)

During testing kasan_populate_early_shadow and kasan_remove_zero_shadow,
if the shadow start and end address in kasan_remove_zero_shadow() is
not aligned to PMD_SIZE, the remain unaligned PTE won't be removed.

In the test case for kasan_remove_zero_shadow():
    shadow_start: 0xffffffb802000000, shadow end: 0xffffffbfbe000000
    3-level page table:
      PUD_SIZE: 0x40000000 PMD_SIZE: 0x200000 PAGE_SIZE: 4K
0xffffffbf80000000 ~ 0xffffffbfbdf80000 will not be removed because
in kasan_remove_pud_table(), kasan_pmd_table(*pud) is true but the
next address is 0xffffffbfbdf80000 which is not aligned to PUD_SIZE.

In the correct condition, this should fallback to the next level
kasan_remove_pmd_table() but the condition flow always continue to skip
the unaligned part.

Fix by correcting the condition when next and addr are neither aligned.

Fixes: 0207df4fa1a86 ("kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN")
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
---
 mm/kasan/init.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index 67051cfae41c..ae9158f7501f 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -372,9 +372,10 @@ static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
 
 		if (kasan_pte_table(*pmd)) {
 			if (IS_ALIGNED(addr, PMD_SIZE) &&
-			    IS_ALIGNED(next, PMD_SIZE))
+			    IS_ALIGNED(next, PMD_SIZE)) {
 				pmd_clear(pmd);
-			continue;
+				continue;
+			}
 		}
 		pte = pte_offset_kernel(pmd, addr);
 		kasan_remove_pte_table(pte, addr, next);
@@ -397,9 +398,10 @@ static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
 
 		if (kasan_pmd_table(*pud)) {
 			if (IS_ALIGNED(addr, PUD_SIZE) &&
-			    IS_ALIGNED(next, PUD_SIZE))
+			    IS_ALIGNED(next, PUD_SIZE)) {
 				pud_clear(pud);
-			continue;
+				continue;
+			}
 		}
 		pmd = pmd_offset(pud, addr);
 		pmd_base = pmd_offset(pud, 0);
@@ -423,9 +425,10 @@ static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
 
 		if (kasan_pud_table(*p4d)) {
 			if (IS_ALIGNED(addr, P4D_SIZE) &&
-			    IS_ALIGNED(next, P4D_SIZE))
+			    IS_ALIGNED(next, P4D_SIZE)) {
 				p4d_clear(p4d);
-			continue;
+				continue;
+			}
 		}
 		pud = pud_offset(p4d, addr);
 		kasan_remove_pud_table(pud, addr, next);
@@ -456,9 +459,10 @@ void kasan_remove_zero_shadow(void *start, unsigned long size)
 
 		if (kasan_p4d_table(*pgd)) {
 			if (IS_ALIGNED(addr, PGDIR_SIZE) &&
-			    IS_ALIGNED(next, PGDIR_SIZE))
+			    IS_ALIGNED(next, PGDIR_SIZE)) {
 				pgd_clear(pgd);
-			continue;
+				continue;
+			}
 		}
 
 		p4d = p4d_offset(pgd, addr);
-- 
2.25.1



             reply	other threads:[~2021-01-03 13:56 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-03 13:56 Lecopzer Chen [this message]
2021-01-03 13:56 ` [PATCH] kasan: fix unaligned address is unhandled in kasan_remove_zero_shadow Lecopzer Chen
2021-01-08 18:25 ` Andrey Konovalov
2021-01-08 18:25   ` Andrey Konovalov

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