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SubjectRe: [PATCH] staging: comedi: use memdup_user
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On Sat, 2017-04-29 at 09:45 +0800, Geliang Tang wrote:
> Use memdup_user() helper instead of open-coding to simplify the code.

While I doubt this is a problem, this loses
the multiplication overflow check for
sizeof(*insns) * insnlist.n_isns

> diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
[]
> @@ -1450,22 +1450,14 @@ static int do_insnlist_ioctl(struct comedi_device *dev,
> return -EFAULT;
>
> data = kmalloc_array(MAX_SAMPLES, sizeof(unsigned int), GFP_KERNEL);
> - if (!data) {
> - ret = -ENOMEM;
> - goto error;
> - }
> -
> - insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL);
> - if (!insns) {
> - ret = -ENOMEM;
> - goto error;
> - }
> + if (!data)
> + return -ENOMEM;
>
> - if (copy_from_user(insns, insnlist.insns,
> - sizeof(*insns) * insnlist.n_insns)) {
> - dev_dbg(dev->class_dev, "copy_from_user failed\n");
> - ret = -EFAULT;
> - goto error;
> + insns = memdup_user(insnlist.insns, sizeof(*insns) * insnlist.n_insns);
> + if (IS_ERR(insns)) {
> + dev_dbg(dev->class_dev, "memdup_user failed\n");
> + kfree(data);
> + return PTR_ERR(insns);
> }
>
> for (i = 0; i < insnlist.n_insns; i++) {

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