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authorMuchun Song <songmuchun@bytedance.com>2022-03-23 00:42:08 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-05-15 20:54:47 +0300
commit2f4e0bf651e3060583b87431889a10390fcb2210 (patch)
tree1ce2b48f1e7b8cd5fed365937adc61625434a68b /mm
parente4db0c3ce0c5d45f386940e1c8319a1d97d7910f (diff)
downloadlinux-2f4e0bf651e3060583b87431889a10390fcb2210.tar.xz
mm: userfaultfd: fix missing cache flush in mcopy_atomic_pte() and __mcopy_atomic()
commit 7c25a0b89a487878b0691e6524fb5a8827322194 upstream. userfaultfd calls mcopy_atomic_pte() and __mcopy_atomic() which do not do any cache flushing for the target page. Then the target page will be mapped to the user space with a different address (user address), which might have an alias issue with the kernel address used to copy the data from the user to. Fix this by insert flush_dcache_page() after copy_from_user() succeeds. Link: https://lkml.kernel.org/r/20220210123058.79206-7-songmuchun@bytedance.com Fixes: b6ebaedb4cb1 ("userfaultfd: avoid mmap_sem read recursion in mcopy_atomic") Fixes: c1a4de99fada ("userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation") Signed-off-by: Muchun Song <songmuchun@bytedance.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Fam Zheng <fam.zheng@bytedance.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lars Persson <lars.persson@axis.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/userfaultfd.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 640ff2bd9a69..6fa66e2111ea 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -53,6 +53,8 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
/* don't free the page */
goto out;
}
+
+ flush_dcache_page(page);
} else {
page = *pagep;
*pagep = NULL;
@@ -572,6 +574,7 @@ retry:
err = -EFAULT;
goto out;
}
+ flush_dcache_page(page);
goto retry;
} else
BUG_ON(page);