linux-kernel - [PATCH 5.4 19/60] riscv: virt_addr_valid must check the address belongs to linear mapping

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Date:   Mon, 15 Feb 2021 16:27:07 +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 <alex@...ti.fr>,
        Atish Patra <atish.patra@....com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 19/60] riscv: virt_addr_valid must check the address belongs to linear mapping

From: Alexandre Ghiti <alex@...ti.fr>

[ Upstream commit 2ab543823322b564f205cb15d0f0302803c87d11 ]

virt_addr_valid macro checks that a virtual address is valid, ie that
the address belongs to the linear mapping and that the corresponding
 physical page exists.

Add the missing check that ensures the virtual address belongs to the
linear mapping, otherwise __virt_to_phys, when compiled with
CONFIG_DEBUG_VIRTUAL enabled, raises a WARN that is interpreted as a
kernel bug by syzbot.

Signed-off-by: Alexandre Ghiti <alex@...ti.fr>
Reviewed-by: Atish Patra <atish.patra@....com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/riscv/include/asm/page.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 3db261c4810fc..6a30794aa1eea 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -119,7 +119,10 @@ extern unsigned long min_low_pfn;
 
 #endif /* __ASSEMBLY__ */
 
-#define virt_addr_valid(vaddr)	(pfn_valid(virt_to_pfn(vaddr)))
+#define virt_addr_valid(vaddr)	({						\
+	unsigned long _addr = (unsigned long)vaddr;				\
+	(unsigned long)(_addr) >= PAGE_OFFSET && pfn_valid(virt_to_pfn(_addr));	\
+})
 
 #define VM_DATA_DEFAULT_FLAGS	(VM_READ | VM_WRITE | \
 				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
-- 
2.27.0