Re: [GIT PULL] USB fixes for 5.9-rc3

[Andy Shevchenko]

On Wed, Aug 26, 2020 at 6:36 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Aug 26, 2020 at 05:02:38PM +0200, Marek Szyprowski wrote:
> > On 26.08.2020 15:43, Greg KH wrote:

> > > Brooke Basile (2):
> > >        USB: gadget: u_f: add overflow checks to VLA macros
> >
> > Sorry, but the above patch breaks USB Ethernet Gadget operation. It also
> > didn't get the proper testing in linux-next (next-20200826 is the first
> > one with this patch).
> >
> > This is how it explodes on Samsung Exynos (ARM 32bit) based board with
> > g_ether module loaded:

> Odd, for a "normal" descriptor, the logic should have remained the same
> as without this patch.

> Brooke, any ideas?

I have an idea.

Does below fix this?


-- 
With Best Regards,
Andy Shevchenko
diff --git a/drivers/usb/gadget/u_f.h b/drivers/usb/gadget/u_f.h
index df4e1dcb357d..0b5c5f0dd073 100644
--- a/drivers/usb/gadget/u_f.h
+++ b/drivers/usb/gadget/u_f.h
@@ -25,8 +25,8 @@
 		size_t offset = 0;					       \
 		if (groupname##__next != SIZE_MAX) {			       \
 			size_t align_mask = __alignof__(type) - 1;	       \
-			size_t offset = (groupname##__next + align_mask)       \
-					 & ~align_mask;			       \
+			offset = (groupname##__next + align_mask) &	       \
+				  ~align_mask;				       \
 			size_t size = array_size(n, sizeof(type));	       \
 			if (check_add_overflow(offset, size,		       \
 					       &groupname##__next)) {          \
@@ -43,8 +43,8 @@
 		size_t offset = 0;						\
 		if (groupname##__next != SIZE_MAX) {				\
 			size_t align_mask = __alignof__(type) - 1;		\
-			size_t offset = (groupname##__next + align_mask)	\
-					 & ~align_mask;				\
+			offset = (groupname##__next + align_mask) &		\
+				  ~align_mask;					\
 			if (check_add_overflow(offset, groupname##_##name##__sz,\
 							&groupname##__next)) {	\
 				groupname##__next = SIZE_MAX;			\