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/[email protected]
Cc: Maximilian Luz <[email protected]>
Cc: Hans de Goede <[email protected]>
Cc: Mark Gross <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
drivers/platform/surface/surface_acpi_notify.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/platform/surface/surface_acpi_notify.c b/drivers/platform/surface/surface_acpi_notify.c
index 44e317970557..50500e562963 100644
--- a/drivers/platform/surface/surface_acpi_notify.c
+++ b/drivers/platform/surface/surface_acpi_notify.c
@@ -355,7 +355,8 @@ static u32 san_evt_bat_nf(struct ssam_event_notifier *nf,
INIT_DELAYED_WORK(&work->work, san_evt_bat_workfn);
work->dev = d->dev;
- memcpy(&work->event, event, sizeof(struct ssam_event) + event->length);
+ work->event = *event;
+ memcpy(work->event.data, event->data, event->length);
queue_delayed_work(san_wq, &work->work, delay);
return SSAM_NOTIF_HANDLED;
--
2.34.1
On Mon, Sep 26, 2022 at 05:40:11PM -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/[email protected]
>
> Cc: Maximilian Luz <[email protected]>
> Cc: Hans de Goede <[email protected]>
> Cc: Mark Gross <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
Reviewed-by: Gustavo A. R. Silva <[email protected]>
Thanks!
--
Gustavo
> ---
> drivers/platform/surface/surface_acpi_notify.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/surface/surface_acpi_notify.c b/drivers/platform/surface/surface_acpi_notify.c
> index 44e317970557..50500e562963 100644
> --- a/drivers/platform/surface/surface_acpi_notify.c
> +++ b/drivers/platform/surface/surface_acpi_notify.c
> @@ -355,7 +355,8 @@ static u32 san_evt_bat_nf(struct ssam_event_notifier *nf,
> INIT_DELAYED_WORK(&work->work, san_evt_bat_workfn);
> work->dev = d->dev;
>
> - memcpy(&work->event, event, sizeof(struct ssam_event) + event->length);
> + work->event = *event;
> + memcpy(work->event.data, event->data, event->length);
>
> queue_delayed_work(san_wq, &work->work, delay);
> return SSAM_NOTIF_HANDLED;
> --
> 2.34.1
>
On 9/27/22 02:40, 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/[email protected]
>
> Cc: Maximilian Luz <[email protected]>
> Cc: Hans de Goede <[email protected]>
> Cc: Mark Gross <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
Thanks!
Reviewed-by: Maximilian Luz <[email protected]>
Regards,
Max
> ---
> drivers/platform/surface/surface_acpi_notify.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/surface/surface_acpi_notify.c b/drivers/platform/surface/surface_acpi_notify.c
> index 44e317970557..50500e562963 100644
> --- a/drivers/platform/surface/surface_acpi_notify.c
> +++ b/drivers/platform/surface/surface_acpi_notify.c
> @@ -355,7 +355,8 @@ static u32 san_evt_bat_nf(struct ssam_event_notifier *nf,
> INIT_DELAYED_WORK(&work->work, san_evt_bat_workfn);
> work->dev = d->dev;
>
> - memcpy(&work->event, event, sizeof(struct ssam_event) + event->length);
> + work->event = *event;
> + memcpy(work->event.data, event->data, event->length);
>
> queue_delayed_work(san_wq, &work->work, delay);
> return SSAM_NOTIF_HANDLED;
Hi,
On 9/27/22 02:40, 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/[email protected]
>
> Cc: Maximilian Luz <[email protected]>
> Cc: Hans de Goede <[email protected]>
> Cc: Mark Gross <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
Thank you for your patch, I've applied this patch to my review-hans
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans
Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.
Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.
Regards,
Hans
> ---
> drivers/platform/surface/surface_acpi_notify.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/surface/surface_acpi_notify.c b/drivers/platform/surface/surface_acpi_notify.c
> index 44e317970557..50500e562963 100644
> --- a/drivers/platform/surface/surface_acpi_notify.c
> +++ b/drivers/platform/surface/surface_acpi_notify.c
> @@ -355,7 +355,8 @@ static u32 san_evt_bat_nf(struct ssam_event_notifier *nf,
> INIT_DELAYED_WORK(&work->work, san_evt_bat_workfn);
> work->dev = d->dev;
>
> - memcpy(&work->event, event, sizeof(struct ssam_event) + event->length);
> + work->event = *event;
> + memcpy(work->event.data, event->data, event->length);
>
> queue_delayed_work(san_wq, &work->work, delay);
> return SSAM_NOTIF_HANDLED;