Re: [PATCH 42/64] net: qede: Use memset_after() for counters
On Mon, Aug 02, 2021 at 02:29:28PM +, 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
> > > ---
> > > 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 mutexqede_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
Re: [PATCH 42/64] net: qede: Use memset_after() for counters
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
> ---
> 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:
struct qede_dev {
...
struct qed_int_info int_info;
/* Smaller private variant of the RTNL lock */
struct mutexqede_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.
-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(>int_info.msix_cnt, 0, sizeof(struct qed_int_info));
> + memset_after(>int_info, 0, msix);
> err3:
> qede_napi_disable_remove(edev);
> err2:
> --
> 2.30.2
>
--
Kees Cook
[PATCH 42/64] net: qede: Use memset_after() for counters
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 --- 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? --- 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(>int_info.msix_cnt, 0, sizeof(struct qed_int_info)); + memset_after(>int_info, 0, msix); err3: qede_napi_disable_remove(edev); err2: -- 2.30.2
