linux-kernel - [PATCH] mm: fix potential pte_unmap

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Message-ID: <20201015121534.50910-1-luoshijie1@huawei.com>
Date:   Thu, 15 Oct 2020 08:15:34 -0400
From:   Shijie Luo <luoshijie1@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>, <linfeilong@...wei.com>,
        <luoshijie1@...wei.com>
Subject: [PATCH] mm: fix potential pte_unmap_unlock pte error

When flags don't have MPOL_MF_MOVE or MPOL_MF_MOVE_ALL bits, code breaks
 and passing origin pte - 1 to pte_unmap_unlock seems like not a good idea.

Signed-off-by: Shijie Luo <luoshijie1@...wei.com>
Signed-off-by: linmiaohe <linmiaohe@...wei.com>
---
 mm/mempolicy.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3fde772ef5ef..01f088630d1d 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -571,7 +571,11 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
 		} else
 			break;
 	}
-	pte_unmap_unlock(pte - 1, ptl);
+
+	if (addr >= end)
+		pte = pte - 1;
+
+	pte_unmap_unlock(pte, ptl);
 	cond_resched();
 
 	if (has_unmovable)
-- 
2.19.1