Messages in this thread | | | From | Dan Williams <> | Date | Wed, 13 Sep 2017 09:22:24 -0700 | Subject | Re: [PATCH] brd: fix overflow in __brd_direct_access |
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On Wed, Sep 13, 2017 at 6:17 AM, Mikulas Patocka <mpatocka@redhat.com> wrote: > The code in __brd_direct_access multiplies the pgoff variable by page size > and divides it by 512. It can cause overflow on 32-bit architectures. The > overflow happens if we create ramdisk larger than 4G and use it as a > sparse device. > > This patch replaces multiplication and division with multiplication by the > number of sectors per page. > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > Fixes: 1647b9b959c7 ("brd: add dax_operations support") > Cc: stable@vger.kernel.org # 4.12+ > > --- > drivers/block/brd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-4.13/drivers/block/brd.c > =================================================================== > --- linux-4.13.orig/drivers/block/brd.c > +++ linux-4.13/drivers/block/brd.c > @@ -339,7 +339,7 @@ static long __brd_direct_access(struct b > > if (!brd) > return -ENODEV; > - page = brd_insert_page(brd, PFN_PHYS(pgoff) / 512); > + page = brd_insert_page(brd, (sector_t)pgoff << PAGE_SECTORS_SHIFT);
Looks good to me, you can add:
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
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