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.
>
> -Kees
>
> > ---
> > drivers/net/ethernet/qlogic/qede/qede_main.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/qlogic/qede/qede_main.c
> b/drivers/net/ethernet/qlogic/qede/qede_main.c
> > index 01ac1e93d27a..309dfe8c94fb 100644
> > --- a/drivers/net/ethernet/qlogic/qede/qede_main.c
> > +++ b/drivers/net/ethernet/qlogic/qede/qede_main.c
> > @@ -2419,7 +2419,7 @@ static int qede_load(struct qede_dev *edev, enum
> qede_load_mode mode,
> > goto out;
> > err4:
> > qede_sync_free_irqs(edev);
> > - memset(&edev->int_info.msix_cnt, 0, sizeof(struct qed_int_info));
> > + memset_after(&edev->int_info, 0, msix);
We will replace the redundant memset with:
edev->int_info.msix_cnt = 0;
> > err3:
> > qede_napi_disable_remove(edev);
> > err2:
> > --
> > 2.30.2
> >
>
> --
> Kees Cook
