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From:   Steven Price <steven.price@arm.com>
To:     Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org
Cc:     Steven Price <steven.price@arm.com>,
        Andy Lutomirski <luto@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
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        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        James Morse <james.morse@arm.com>,
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        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will@kernel.org>, x86@kernel.org,
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        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Mark Rutland <Mark.Rutland@arm.com>,
        "Liang, Kan" <kan.liang@linux.intel.com>
Subject: [PATCH v16 14/25] mm: pagewalk: fix termination condition in walk_pte_range()
Date:   Fri,  6 Dec 2019 13:53:05 +0000
Message-Id: <20191206135316.47703-15-steven.price@arm.com>
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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.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 mm/pagewalk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 1b9a3ba24c51..88104ab00a97 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -18,9 +18,9 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		err = ops->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++;
 	}
 
-- 
2.20.1