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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, hughd@google.com,
	joel@joelfernandes.org, linux-mm@kvack.org,
	mike.kravetz@oracle.com, mm-commits@vger.kernel.org,
	peterx@redhat.com, stable@vger.kernel.org,
	torvalds@linux-foundation.org
Subject: [patch 02/13] mm/hugetlb: fix cow where page writtable in child
Date: Fri, 14 May 2021 17:27:07 -0700	[thread overview]
Message-ID: <20210515002707.LZb1SqAkO%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210514172634.9018621171d5334ceee97e95@linux-foundation.org>

From: Peter Xu <peterx@redhat.com>
Subject: mm/hugetlb: fix cow where page writtable in child

When rework early cow of pinned hugetlb pages, we moved huge_ptep_get()
upper but overlooked a side effect that the huge_ptep_get() will fetch the
pte after wr-protection.  After moving it upwards, we need explicit
wr-protect of child pte or we will keep the write bit set in the child
process, which could cause data corrution where the child can write to the
original page directly.

This issue can also be exposed by "memfd_test hugetlbfs" kselftest.

Link: https://lkml.kernel.org/r/20210503234356.9097-3-peterx@redhat.com
Fixes: 4eae4efa2c299 ("hugetlb: do early cow when page pinned on src mm")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |    1 +
 1 file changed, 1 insertion(+)

--- a/mm/hugetlb.c~mm-hugetlb-fix-cow-where-page-writtable-in-child
+++ a/mm/hugetlb.c
@@ -4056,6 +4056,7 @@ again:
 				 * See Documentation/vm/mmu_notifier.rst
 				 */
 				huge_ptep_set_wrprotect(src, addr, src_pte);
+				entry = huge_pte_wrprotect(entry);
 			}
 
 			page_dup_rmap(ptepage, true);
_


  parent reply	other threads:[~2021-05-15  0:27 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-15  0:26 incoming Andrew Morton
2021-05-15  0:27 ` [patch 01/13] mm/hugetlb: fix F_SEAL_FUTURE_WRITE Andrew Morton
2021-05-15  0:27 ` Andrew Morton [this message]
2021-05-15  0:27 ` [patch 03/13] mm, slub: move slub_debug static key enabling outside slab_mutex Andrew Morton
2021-05-15  0:27 ` [patch 04/13] kernel/resource: fix return code check in __request_free_mem_region Andrew Morton
2021-05-15  0:27 ` [patch 05/13] squashfs: fix divide error in calculate_skip() Andrew Morton
2021-05-15  0:27 ` [patch 06/13] userfaultfd: release page in error path to avoid BUG_ON Andrew Morton
2021-05-15  0:27 ` [patch 07/13] ksm: revert "use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()" Andrew Morton
2021-05-15  0:27 ` [patch 08/13] mm: fix struct page layout on 32-bit systems Andrew Morton
2021-05-15  0:27 ` [patch 09/13] kasan: fix unit tests with CONFIG_UBSAN_LOCAL_BOUNDS enabled Andrew Morton
2021-05-15  0:27 ` [patch 10/13] mm/filemap: fix readahead return types Andrew Morton
2021-05-15  0:27 ` [patch 11/13] hfsplus: prevent corruption in shrinking truncate Andrew Morton
2021-05-15  0:27 ` [patch 12/13] docs: admin-guide: update description for kernel.modprobe sysctl Andrew Morton
2021-05-15  0:27 ` [patch 13/13] mm/ioremap: fix iomap_max_page_shift Andrew Morton

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