linux-kernel - [PATCH 5.16 052/186] riscv: Fix config KASAN && SPARSEMEM && !SPARSE

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Date:   Mon,  7 Mar 2022 10:18:10 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Alexandre Ghiti <alexandre.ghiti@...onical.com>,
        Palmer Dabbelt <palmer@...osinc.com>
Subject: [PATCH 5.16 052/186] riscv: Fix config KASAN && SPARSEMEM && !SPARSE_VMEMMAP

From: Alexandre Ghiti <alexandre.ghiti@...onical.com>

commit a3d328037846d013bb4c7f3777241e190e4c75e1 upstream.

In order to get the pfn of a struct page* when sparsemem is enabled
without vmemmap, the mem_section structures need to be initialized which
happens in sparse_init.

But kasan_early_init calls pfn_to_page way before sparse_init is called,
which then tries to dereference a null mem_section pointer.

Fix this by removing the usage of this function in kasan_early_init.

Fixes: 8ad8b72721d0 ("riscv: Add KASAN support")
Signed-off-by: Alexandre Ghiti <alexandre.ghiti@...onical.com>
Cc: stable@...r.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/riscv/mm/kasan_init.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -22,8 +22,7 @@ asmlinkage void __init kasan_early_init(
 
 	for (i = 0; i < PTRS_PER_PTE; ++i)
 		set_pte(kasan_early_shadow_pte + i,
-			mk_pte(virt_to_page(kasan_early_shadow_page),
-			       PAGE_KERNEL));
+			pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL));
 
 	for (i = 0; i < PTRS_PER_PMD; ++i)
 		set_pmd(kasan_early_shadow_pmd + i,