[PATCH] usb: core: Warn if an URB's transfer_buffer is on stack

[Florian Fainelli <f.fainelli@gmail.com>]

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_start_wait_urb() for
urb->transfer_buffer to be located on the stack.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/usb/core/message.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 2184ef40a82a..abefddbe9243 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -8,6 +8,7 @@
 #include <linux/pci.h>	/* for scatterlist macros */
 #include <linux/usb.h>
 #include <linux/module.h>
+#include <linux/sched/task_stack.h> /* for object_is_on_stack */
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/timer.h>
@@ -50,6 +51,8 @@ static int usb_start_wait_urb(struct urb *urb, int timeout, int *actual_length)
 	unsigned long expire;
 	int retval;
 
+	WARN_ON(object_is_on_stack(urb->transfer_buffer));
+
 	init_completion(&ctx.done);
 	urb->context = &ctx;
 	urb->actual_length = 0;
-- 
2.11.0