2009-11-21 18:38:18

by Roel Kluin

Subject: [PATCH] wusb: Use sizeof struct rather than pointer

The sizeof the struct should be used rather than sizeof the pointer

Signed-off-by: Roel Kluin <[email protected]>
---
drivers/usb/wusbcore/security.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

Unless I am mistaken?

diff --git a/drivers/usb/wusbcore/security.c b/drivers/usb/wusbcore/security.c
index 4516c36..857f6e9 100644
--- a/drivers/usb/wusbcore/security.c
+++ b/drivers/usb/wusbcore/security.c
@@ -213,7 +213,7 @@ int wusb_dev_sec_add(struct wusbhc *wusbhc,

result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
0, secd, sizeof(struct usb_security_descriptor));
- if (result < sizeof(secd)) {
+ if (result < sizeof(*secd)) {
dev_err(dev, "Can't read security descriptor or "
"not enough data: %d\n", result);
goto out;

2009-11-24 00:37:50

by Andrew Morton

Subject: Re: [PATCH] wusb: Use sizeof struct rather than pointer

On Sat, 21 Nov 2009 19:51:14 +0100
Roel Kluin <[email protected]> wrote:

> The sizeof the struct should be used rather than sizeof the pointer
>
> Signed-off-by: Roel Kluin <[email protected]>
> ---
> drivers/usb/wusbcore/security.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> Unless I am mistaken?
>
> diff --git a/drivers/usb/wusbcore/security.c b/drivers/usb/wusbcore/security.c
> index 4516c36..857f6e9 100644
> --- a/drivers/usb/wusbcore/security.c
> +++ b/drivers/usb/wusbcore/security.c
> @@ -213,7 +213,7 @@ int wusb_dev_sec_add(struct wusbhc *wusbhc,
>
> result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
> 0, secd, sizeof(struct usb_security_descriptor));
> - if (result < sizeof(secd)) {
> + if (result < sizeof(*secd)) {
> dev_err(dev, "Can't read security descriptor or "
> "not enough data: %d\n", result);
> goto out;

ick, code's a bit of a mess.

This:

--- a/drivers/usb/wusbcore/security.c~wusb-use-sizeof-struct-rather-than-pointer
+++ a/drivers/usb/wusbcore/security.c
@@ -205,15 +205,15 @@ int wusb_dev_sec_add(struct wusbhc *wusb
const void *itr, *top;
char buf[64];

- secd = kmalloc(sizeof(struct usb_security_descriptor), GFP_KERNEL);
+ secd = kmalloc(sizeof(*secd), GFP_KERNEL);
if (secd == NULL) {
result = -ENOMEM;
goto out;
}

- result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
- 0, secd, sizeof(struct usb_security_descriptor));
- if (result < sizeof(secd)) {
+ result = usb_get_descriptor(usb_dev, USB_DT_SECURITY, 0, secd,
+ sizeof(*secd));
+ if (result < sizeof(*secd)) {
dev_err(dev, "Can't read security descriptor or "
"not enough data: %d\n", result);
goto out;
_

at least makes things consistent.

But I wonder if the code will still work. Because we then go on to do

secd_size = le16_to_cpu(secd->wTotalLength);
secd = krealloc(secd, secd_size, GFP_KERNEL);

which implies (to me) that the thing we read from the device might
indeed have been smaller than we expected, in which case the
newly-fixed check will cause a failure.

That's probably not the case, but it needs checking by someone who
knows what's going on here, please

2009-11-24 02:23:51

by David Vrabel

Subject: Re: [PATCH] wusb: Use sizeof struct rather than pointer

Andrew Morton wrote:
>
> But I wonder if the code will still work. Because we then go on to do
>
> secd_size = le16_to_cpu(secd->wTotalLength);
> secd = krealloc(secd, secd_size, GFP_KERNEL);
>
> which implies (to me) that the thing we read from the device might
> indeed have been smaller than we expected, in which case the
> newly-fixed check will cause a failure.

We first read the security descriptor which tells use the total length
of the security descriptor plus all the following encryption type
descriptors. Your revised patch is fine.

David