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SubjectRe: [PATCH v2 net] nfp: cast sizeof() to int when comparing with error code


On Mon, 25 Jun 2018, Joe Perches wrote:

> On Tue, 2018-06-26 at 09:16 +0800, Chengguang Xu wrote:
> > sizeof() will return unsigned value so in the error check
> > negative error code will be always larger than sizeof().
>
> This looks like a general class of error in the kernel
> where a signed result that could be returning a -errno
> is tested against < or <= sizeof()
>
> A couple examples:
>
> drivers/input/mouse/elan_i2c_smbus.c:
>
> len = i2c_smbus_read_block_data(client,
> ETP_SMBUS_IAP_PASSWORD_READ,
> val);
> if (len < sizeof(u16)) {
>
> i2c_smbus_read_block_data can return a negative errno
>
>
> net/smc/smc_clc.c:
>
> len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
> sizeof(struct smc_clc_msg_decline));
> if (len < sizeof(struct smc_clc_msg_decline))
>
> where kernel_sendmsg can return a negative errno
>
> There are probably others, I didn't look hard.
>
> Perhaps a cocci script to find these could be generated?

Here's another one:

drivers/usb/serial/ir-usb.c
@@ -126,13 +126,8 @@ irda_usb_find_class_desc(struct usb_seri
if (!desc)
return NULL;

- ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
- USB_REQ_CS_IRDA_GET_CLASS_DESC,
- USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
- 0, ifnum, desc, sizeof(*desc), 1000);

dev_dbg(&serial->dev->dev, "%s - ret=%d\n", __func__, ret);
- if (ret < sizeof(*desc)) {
dev_dbg(&serial->dev->dev,
"%s - class descriptor read %s (%d)\n", __func__,
(ret < 0) ? "failed" : "too short", ret);

There are other results, but I haven't checked all of them.

julia

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