linux-kernel - [PATCH] xen: fix sparse warning in page.h

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Message-Id: <1417760217-16977-1-git-send-email-jgross@suse.com>
Date:	Fri,  5 Dec 2014 07:16:57 +0100
From:	Juergen Gross <jgross@...e.com>
To:	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
	konrad.wilk@...cle.com, david.vrabel@...rix.com,
	boris.ostrovsky@...cle.com
Cc:	Juergen Gross <jgross@...e.com>
Subject: [PATCH] xen: fix sparse warning in page.h

The inline function mfn_to_pfn_no_overrides() uses __get_user() to
access the machine_to_phys_mapping array to avoid crashes when
using out of bounds indices e.g. for I/O addresses.

Avoid sparse warnings by attributing the accessed address with __user.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/include/asm/xen/page.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index f5d5de4..6deff84 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -113,6 +113,7 @@ static inline unsigned long mfn_to_pfn_no_overrides(unsigned long mfn)
 {
 	unsigned long pfn;
 	int ret;
+	unsigned long __user *addr;
 
 	if (xen_feature(XENFEAT_auto_translated_physmap))
 		return mfn;
@@ -125,7 +126,8 @@ static inline unsigned long mfn_to_pfn_no_overrides(unsigned long mfn)
 	 * In such cases it doesn't matter what we return (we return garbage),
 	 * but we must handle the fault without crashing!
 	 */
-	ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
+	addr = (unsigned long __user *)(&machine_to_phys_mapping[mfn]);
+	ret = __get_user(pfn, addr);
 	if (ret < 0)
 		return ~0;
 
-- 
2.1.2

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