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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hongxiang Lou <louhongxiang@huawei.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Shakeel Butt <shakeelb@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Michel Lespinasse <walken@google.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Wei Yang <richard.weiyang@linux.alibaba.com>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        Brian Geffon <bgeffon@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 176/247] mm/rmap: fix potential pte_unmap on an not mapped pte
Date:   Mon,  1 Mar 2021 17:13:16 +0100
Message-Id: <20210301161040.266545926@linuxfoundation.org>
In-Reply-To: <20210301161031.684018251@linuxfoundation.org>
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From: Miaohe Lin <linmiaohe@huawei.com>

[ Upstream commit 5d5d19eda6b0ee790af89c45e3f678345be6f50f ]

For PMD-mapped page (usually THP), pvmw->pte is NULL.  For PTE-mapped THP,
pvmw->pte is mapped.  But for HugeTLB pages, pvmw->pte is not mapped and
set to the relevant page table entry.  So in page_vma_mapped_walk_done(),
we may do pte_unmap() for HugeTLB pte which is not mapped.  Fix this by
checking pvmw->page against PageHuge before trying to do pte_unmap().

Link: https://lkml.kernel.org/r/20210127093349.39081-1-linmiaohe@huawei.com
Fixes: ace71a19cec5 ("mm: introduce page_vma_mapped_walk()")
Signed-off-by: Hongxiang Lou <louhongxiang@huawei.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michel Lespinasse <walken@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/rmap.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 988d176472df7..d7d6d4eb17949 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -214,7 +214,8 @@ struct page_vma_mapped_walk {
 
 static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)
 {
-	if (pvmw->pte)
+	/* HugeTLB pte is set to the relevant page table entry without pte_mapped. */
+	if (pvmw->pte && !PageHuge(pvmw->page))
 		pte_unmap(pvmw->pte);
 	if (pvmw->ptl)
 		spin_unlock(pvmw->ptl);
-- 
2.27.0