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:

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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@chromium.org

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