| Message ID | 20210504222134.OVXQ7jyUz%akpm@linux-foundation.org |
|---|---|
| State | New |
| Headers | show |
| Series | + mm-hugetlb-fix-cow-where-page-writtable-in-child.patch added to -mm tree | expand |
--- a/mm/hugetlb.c~mm-hugetlb-fix-cow-where-page-writtable-in-child +++ a/mm/hugetlb.c @@ -3898,6 +3898,7 @@ 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);
The patch titled Subject: mm/hugetlb: fix cow where page writtable in child has been added to the -mm tree. Its filename is mm-hugetlb-fix-cow-where-page-writtable-in-child.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-fix-cow-where-page-writtable-in-child.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-fix-cow-where-page-writtable-in-child.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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: <stable@vger.kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- mm/hugetlb.c | 1 + 1 file changed, 1 insertion(+)