[PATCH v1 1/1] riscv: mm: add missing memcpy in kasan_init

From: panqinglin2020@iscas.ac.cn
To: atishp@atishpatra.org
Cc: alex@ghiti.fr, linux-riscv@lists.infradead.org,
	palmer@dabbelt.com, Qinglin Pan <panqinglin2020@iscas.ac.cn>
Subject: [PATCH v1 1/1] riscv: mm: add missing memcpy in kasan_init
Date: Sun,  9 Oct 2022 16:30:50 +0800	[thread overview]
Message-ID: <20221009083050.3814850-1-panqinglin2020@iscas.ac.cn> (raw)
In-Reply-To: <CAOnJCU+GHzFSzSdvZKBrFeF4WqPvC5w0r1f4r3S8hLbOagPKgA@mail.gmail.com>

From: Qinglin Pan <panqinglin2020@iscas.ac.cn>

Hi Atish,

It seems that the panic is due to the missing memcpy during kasan_init.
Could you please check whether this patch is helpful?

When doing kasan_populate, the new allocated base_pud/base_p4d should
contain kasan_early_shadow_{pud, p4d}'s content. Add the missing memcpy
to avoid page fault when read/write kasan shadow region.

Tested on:
 - qemu with sv57 and CONFIG_KASAN on.
 - qemu with sv48 and CONFIG_KASAN on.

Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>
---
 arch/riscv/mm/kasan_init.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index a22e418dbd82..e1226709490f 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -113,6 +113,8 @@ static void __init kasan_populate_pud(pgd_t *pgd,
 		base_pud = pt_ops.get_pud_virt(pfn_to_phys(_pgd_pfn(*pgd)));
 	} else if (pgd_none(*pgd)) {
 		base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
+		memcpy(base_pud, (void *)kasan_early_shadow_pud,
+			sizeof(pud_t) * PTRS_PER_PUD);
 	} else {
 		base_pud = (pud_t *)pgd_page_vaddr(*pgd);
 		if (base_pud == lm_alias(kasan_early_shadow_pud)) {
@@ -173,8 +175,11 @@ static void __init kasan_populate_p4d(pgd_t *pgd,
 		base_p4d = pt_ops.get_p4d_virt(pfn_to_phys(_pgd_pfn(*pgd)));
 	} else {
 		base_p4d = (p4d_t *)pgd_page_vaddr(*pgd);
-		if (base_p4d == lm_alias(kasan_early_shadow_p4d))
+		if (base_p4d == lm_alias(kasan_early_shadow_p4d)) {
 			base_p4d = memblock_alloc(PTRS_PER_PUD * sizeof(p4d_t), PAGE_SIZE);
+			memcpy(base_p4d, (void *)kasan_early_shadow_p4d,
+				sizeof(p4d_t) * PTRS_PER_P4D);
+		}
 	}
 
 	p4dp = base_p4d + p4d_index(vaddr);
-- 
2.35.1


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