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:

quoted

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 <redacted>
---
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

quoted

---
 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

quoted

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,

quoted

 	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; 

quoted

 err3:
 	qede_napi_disable_remove(edev);
 err2:
--
2.30.2

--
Kees Cook