On Fri, Mar 24, 2023 at 09:50:54AM +0800, Shiyang Ruan wrote: > > > 在 2023/3/24 6:11, Andrew Morton 写道: > > On Thu, 23 Mar 2023 14:50:38 +0800 Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx> wrote: > > > > > > > > > > > 在 2023/3/23 7:03, Andrew Morton 写道: > > > > On Wed, 22 Mar 2023 11:11:09 +0000 Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx> wrote: > > > > > > > > > unshare copies data from source to destination. But if the source is > > > > > HOLE or UNWRITTEN extents, we should zero the destination, otherwise the > > > > > result will be unexpectable. > > > > > > > > Please provide much more detail on the user-visible effects of the bug. > > > > For example, are we leaking kernel memory contents to userspace? > > > > > > This fixes fail of generic/649. > > > > OK, but this doesn't really help. I'm trying to determine whether this > > fix should be backported into -stable kernels and whether it should be > > fast-tracked into Linus's current -rc tree. > > > > But to determine this I (and others) need to know what effect the bug > > has upon our users. > > I didn't get any bug report form users. I just found this by running > xfstests. The phenomenon of this problem is: if we funshare a reflinked > file which contains HOLE extents, the result of the HOLE extents should be > zero but actually not (unexpectable data). You still aren't answering the question. If this did happen to a user, what would they see in the file? Random data? Something somebody else wrote some time ago? A copy of /etc/passwd, perhaps? A copy of your credit card number?
