On Mon, Aug 02, 2021 at 02:29:28PM +0000, Shai Malin wrote:
>
> On Tue, Jul 31, 2021 at 07:07:00PM -0300, Kees Cook wrote:
> > On Tue, Jul 27, 2021 at 01:58:33PM -0700, Kees Cook wrote:
> > > In preparation for FORTIFY_SOURCE performing compile-time and run-time
> > > field bounds checking for memset(), avoid intentionally writing across
> > > neighboring fields.
> > >
> > > Use memset_after() so memset() doesn't get confused about writing
> > > beyond the destination member that is intended to be the starting point
> > > of zeroing through the end of the struct.
> > >
> > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> > > ---
> > > The old code seems to be doing the wrong thing: starting from not the
> > > first member, but sized for the whole struct. Which is correct?
> >
> > Quick ping on this question.
> >
> > The old code seems to be doing the wrong thing: it starts from the second
> > member and writes beyond int_info, clobbering qede_lock:
>
> Thanks for highlighting the problem, but actually, the memset is redundant.
> We will remove it so the change will not be needed.
>
> >
> > struct qede_dev {
> > ...
> > struct qed_int_info int_info;
> >
> > /* Smaller private variant of the RTNL lock */
> > struct mutex qede_lock;
> > ...
> >
> >
> > struct qed_int_info {
> > struct msix_entry *msix;
> > u8 msix_cnt;
> >
> > /* This should be updated by the protocol driver */
> > u8 used_cnt;
> > };
> >
> > Should this also clear the "msix" member, or should this not write
> > beyond int_info? This patch does the latter.
>
> It should clear only the msix_cnt, no need to clear the entire
> qed_int_info structure.
Should used_cnt be cleared too? It is currently. Better yet, what patch
do you suggest I replace this proposed one with? :)
Thanks for looking at this!
-Kees
--
Kees Cook
