On Sun, 23 Apr 2017, Florian Fainelli wrote:
> We see a large number of fixes to several drivers to remove the usage of
> on-stack buffers feeding into USB transfer functions. Make it easier to spot
> the offenders by adding a warning in usb_hcd_map_urb_for_dma() checking that
> urb->transfer_buffer is not a stack object.
>
> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> ---
> Changes in v2:
>
> - moved the check from usb_start_wait_urb() to usb_hcd_map_urb_for_dma()
You probably should add a similar check to the pathway that maps
urb->setup_packet, for the sake of consistency.
Alan Stern
> drivers/usb/core/hcd.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index 49550790a3cb..ce9063ce906a 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -26,6 +26,7 @@
> #include <linux/module.h>
> #include <linux/version.h>
> #include <linux/kernel.h>
> +#include <linux/sched/task_stack.h>
> #include <linux/slab.h>
> #include <linux/completion.h>
> #include <linux/utsname.h>
> @@ -1587,6 +1588,9 @@ int usb_hcd_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
> } else if (is_vmalloc_addr(urb->transfer_buffer)) {
> WARN_ONCE(1, "transfer buffer not dma capable\n");
> ret = -EAGAIN;
> + } else if (object_is_on_stack(urb->transfer_buffer)) {
> + WARN_ONCE(1, "transfer buffer is on stack\n");
> + ret = -EAGAIN;
> } else {
> urb->transfer_dma = dma_map_single(
> hcd->self.sysdev,
>
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