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SubjectRe: [PATCH] s390/qeth: Split memcpy() of struct qeth_ipacmd_addr_change flexible array
On Mon, Sep 26, 2022 at 05:39:53PM -0700, Kees Cook wrote:
> To work around a misbehavior of the compiler's ability to see into
> composite flexible array structs (as detailed in the coming memcpy()
> hardening series[1]), split the memcpy() of the header and the payload
> so no false positive run-time overflow warning will be generated.
>
> [1] https://lore.kernel.org/linux-hardening/20220901065914.1417829-2-keescook@chromium.org/
>
> Cc: Alexandra Winter <wintera@linux.ibm.com>
> Cc: Wenjia Zhang <wenjia@linux.ibm.com>
> Cc: Heiko Carstens <hca@linux.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
> Cc: Sven Schnelle <svens@linux.ibm.com>
> Cc: linux-s390@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks!
--
Gustavo

> ---
> drivers/s390/net/qeth_l2_main.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
> index 2d4436cbcb47..0ce635b7b472 100644
> --- a/drivers/s390/net/qeth_l2_main.c
> +++ b/drivers/s390/net/qeth_l2_main.c
> @@ -1530,8 +1530,8 @@ static void qeth_addr_change_event(struct qeth_card *card,
> else
> INIT_DELAYED_WORK(&data->dwork, qeth_l2_dev2br_worker);
> data->card = card;
> - memcpy(&data->ac_event, hostevs,
> - sizeof(struct qeth_ipacmd_addr_change) + extrasize);
> + data->ac_event = *hostevs;
> + memcpy(data->ac_event.entry, hostevs->entry, extrasize);
> queue_delayed_work(card->event_wq, &data->dwork, 0);
> }
>
> --
> 2.34.1
>

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