Messages in this thread | | | Date | Wed, 8 Dec 2021 11:00:41 +0800 | Subject | Re: [PATCH] usb: core: hcd: fix bug: application of sizeof to pointer | From | Guo Zhengkui <> |
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On 2021/12/8 6:21, Alan Stern wrote: > 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@vivo.com> >>> --- >>> 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.) >
Sorry for my carelessness. It should be sizeof(vaddr).
> 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).
OK, I will commit another patch to fix this problem. Do you mind I add a "Suggested-by" tag of your name (Alan Stern) in this new patch?
Zhengkui
> > Alan Stern >
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