On Tue, Dec 07, 2021 at 03:40:37PM +0100, Greg Kroah-Hartman wrote: > On Tue, Dec 07, 2021 at 09:53:47PM +0800, Guo Zhengkui wrote: > > Fix following error: > > ./drivers/usb/core/hcd.c:1284:38-44: ERROR: > > application of sizeof to pointer. > > What generated this error? > > > > > Use sizeof(*vaddr) instead. > > > > Signed-off-by: Guo Zhengkui <guozhengkui@xxxxxxxx> > > --- > > drivers/usb/core/hcd.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c > > index 4d326ee12c36..996d5273cf60 100644 > > --- a/drivers/usb/core/hcd.c > > +++ b/drivers/usb/core/hcd.c > > @@ -1281,7 +1281,7 @@ static int hcd_alloc_coherent(struct usb_bus *bus, > > return -EFAULT; > > } > > > > - vaddr = hcd_buffer_alloc(bus, size + sizeof(vaddr), > > + vaddr = hcd_buffer_alloc(bus, size + sizeof(*vaddr), > > I think you just broke the code. > > Look at this closer and see what the function is doing with this buffer > and if you still think your patch is correct, please rewrite the > changelog text to explain why it is so (hint, just using the output of > coccinelle isn't ok.) Although the patch is definitely wrong, the code could stand to be improved. The value stored at the end of the buffer is *vaddr_handle converted to an unsigned long, but the space reserved for this value is sizeof(vaddr) -- which doesn't make much sense since vaddr is a pointer to unsigned char. The code implicitly relies on the fact that unsigned long takes up the same amount of space as a pointer. Readers wouldn't have to stop and figure this out if the amount of reserved space was simply set to sizeof(unsigned long) rather than sizeof(vaddr). Alan Stern
