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| author | Peter Xu <peterx@redhat.com> | 2021-05-14 17:27:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-05-14 19:41:32 -0700 |
| commit | 84894e1c42e9f25c17f2888e0c0e1505cb727538 (patch) | |
| tree | 8eef1e02cf8d88f9fc40199a1df333c8bb4033d8 /mm/hugetlb.c | |
| parent | 22247efd822e6d263f3c8bd327f3f769aea9b1d9 (diff) | |
| download | lwn-84894e1c42e9f25c17f2888e0c0e1505cb727538.tar.gz lwn-84894e1c42e9f25c17f2888e0c0e1505cb727538.zip | |
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 3db405dea3dc..95918f410c0f 100644 --- a/mm/hugetlb.c +++ b/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); |