| Message ID | alpine.LRH.2.02.1709130909570.1354@file01.intranet.prod.int.rdu2.redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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>
On 09/13/2017 07:17 AM, Mikulas Patocka 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. Thanks, applied with Dan's ack.
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); if (!page) return -ENOSPC; *kaddr = page_address(page);
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(-)