linux-kernel - [PATCH] arm64: trap illegal translations in __virt_to

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Date:   Mon, 7 Jan 2019 19:21:20 +0800
From:   Miles Chen <miles.chen@...iatek.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <wsd_upstream@...iatek.com>,
        Miles Chen <miles.chen@...iatek.com>
Subject: [PATCH] arm64: trap illegal translations in __virt_to_phys()

Current __virt_to_phys() only print warning messages for non-linear
addresses. It's hard to catch all warnings by those messages. So add a
VIRTUAL_BUG_ON() to trap all non-linear and non-symbol addresses
(e.g., stack addresses)

Tested by pass stack addresses and symbol addresses to __pa(). Result:
stack addresses: kernel BUG()
symbol addresses: kernel warning message

Maybe we should trap all non-linear address translations in the future.

Signed-off-by: Miles Chen <miles.chen@...iatek.com>
---
 arch/arm64/mm/physaddr.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/mm/physaddr.c b/arch/arm64/mm/physaddr.c
index 67a9ba9eaa96..f6b935dad19c 100644
--- a/arch/arm64/mm/physaddr.c
+++ b/arch/arm64/mm/physaddr.c
@@ -14,6 +14,11 @@ phys_addr_t __virt_to_phys(unsigned long x)
 	      (void *)x,
 	      (void *)x);
 
+	/* trap all non-linear and non-symbol addresses */
+	VIRTUAL_BUG_ON(!__is_lm_address(x) &&
+			(x < (unsigned long)KERNEL_START ||
+			 x > (unsigned long)KERNEL_END));
+
 	return __virt_to_phys_nodebug(x);
 }
 EXPORT_SYMBOL(__virt_to_phys);
-- 
2.18.0