linux-kernel - [PATCH -next v4 2/7] arm64: fix types in copy

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Date:   Wed, 20 Apr 2022 03:04:13 +0000
From:   Tong Tiangen <tongtiangen@...wei.com>
To:     Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Robin Murphy <robin.murphy@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>, <x86@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>
CC:     <linuxppc-dev@...ts.ozlabs.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Xie XiuQi <xiexiuqi@...wei.com>,
        Guohanjun <guohanjun@...wei.com>,
        Tong Tiangen <tongtiangen@...wei.com>
Subject: [PATCH -next v4 2/7] arm64: fix types in copy_highpage()

In copy_highpage() the `kto` and `kfrom` local variables are pointers to
struct page, but these are used to hold arbitrary pointers to kernel memory
. Each call to page_address() returns a void pointer to memory associated
with the relevant page, and copy_page() expects void pointers to this
memory.

This inconsistency was introduced in commit 2563776b41c3 ("arm64: mte:
Tags-aware copy_{user_,}highpage() implementations") and while this
doesn't appear to be harmful in practice it is clearly wrong.

Correct this by making `kto` and `kfrom` void pointers.

Fixes: 2563776b41c3 ("arm64: mte: Tags-aware copy_{user_,}highpage() implementations")
Signed-off-by: Tong Tiangen <tongtiangen@...wei.com>
Acked-by: Mark Rutland <mark.rutland@....com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 arch/arm64/mm/copypage.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c
index b5447e53cd73..0dea80bf6de4 100644
--- a/arch/arm64/mm/copypage.c
+++ b/arch/arm64/mm/copypage.c
@@ -16,8 +16,8 @@
 
 void copy_highpage(struct page *to, struct page *from)
 {
-	struct page *kto = page_address(to);
-	struct page *kfrom = page_address(from);
+	void *kto = page_address(to);
+	void *kfrom = page_address(from);
 
 	copy_page(kto, kfrom);
 
-- 
2.25.1