linux-kernel - [PATCH AUTOSEL 4.19 067/206] mm: pagewalk: fix termination condition in walk_pte

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Date:   Thu, 17 Sep 2020 22:05:43 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Steven Price <steven.price@....com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Alexandre Ghiti <alex@...ti.fr>,
        Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "David S . Miller" <davem@...emloft.net>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        James Hogan <jhogan@...nel.org>,
        James Morse <james.morse@....com>,
        Jerome Glisse <jglisse@...hat.com>,
        "Liang, Kan" <kan.liang@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Burton <paul.burton@...s.com>,
        Paul Mackerras <paulus@...ba.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Russell King <linux@...linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vineet Gupta <vgupta@...opsys.com>,
        Will Deacon <will@...nel.org>, Zong Li <zong.li@...ive.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>, linux-mm@...ck.org
Subject: [PATCH AUTOSEL 4.19 067/206] mm: pagewalk: fix termination condition in walk_pte_range()

From: Steven Price <steven.price@....com>

[ Upstream commit c02a98753e0a36ba65a05818626fa6adeb4e7c97 ]

If walk_pte_range() is called with a 'end' argument that is beyond the
last page of memory (e.g.  ~0UL) then the comparison between 'addr' and
'end' will always fail and the loop will be infinite.  Instead change the
comparison to >= while accounting for overflow.

Link: http://lkml.kernel.org/r/20191218162402.45610-15-steven.price@arm.com
Signed-off-by: Steven Price <steven.price@....com>
Cc: Albert Ou <aou@...s.berkeley.edu>
Cc: Alexandre Ghiti <alex@...ti.fr>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Christian Borntraeger <borntraeger@...ibm.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: David S. Miller <davem@...emloft.net>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: James Hogan <jhogan@...nel.org>
Cc: James Morse <james.morse@....com>
Cc: Jerome Glisse <jglisse@...hat.com>
Cc: "Liang, Kan" <kan.liang@...ux.intel.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Paul Burton <paul.burton@...s.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Paul Walmsley <paul.walmsley@...ive.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ralf Baechle <ralf@...ux-mips.org>
Cc: Russell King <linux@...linux.org.uk>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vasily Gorbik <gor@...ux.ibm.com>
Cc: Vineet Gupta <vgupta@...opsys.com>
Cc: Will Deacon <will@...nel.org>
Cc: Zong Li <zong.li@...ive.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 mm/pagewalk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index c3084ff2569d2..3c0930d94a295 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -15,9 +15,9 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
 		if (err)
 		       break;
-		addr += PAGE_SIZE;
-		if (addr == end)
+		if (addr >= end - PAGE_SIZE)
 			break;
+		addr += PAGE_SIZE;
 		pte++;
 	}
 
-- 
2.25.1