| Message ID | 20220210123058.79206-7-songmuchun@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Fix some cache flush bugs | expand |
On 2/10/22 04:30, Muchun Song wrote: > The 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. > > 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> > --- > mm/userfaultfd.c | 3 +++ > 1 file changed, 3 insertions(+) Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 0780c2a57ff1..6ccc534d1c1c 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -150,6 +150,8 @@ 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; @@ -625,6 +627,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, err = -EFAULT; goto out; } + flush_dcache_page(page); goto retry; } else BUG_ON(page);
The 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. 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> --- mm/userfaultfd.c | 3 +++ 1 file changed, 3 insertions(+)