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s390/hmcdrv: Replace kmalloc() + copy_from_user() with memdup_user_nul()

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Replace kmalloc() followed by copy_from_user() with memdup_user_nul() to
improve and simplify hmcdrv_dev_write(). Remove the manual
NUL-termination.

No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Thorsten Blum 2025-09-05 13:02:23 +02:00 committed by Alexander Gordeev
parent f5507aefc9
commit 5450abb0de
1 changed files with 6 additions and 13 deletions
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19
drivers/s390/char/hmcdrv_dev.c
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@ -244,24 +244,17 @@ static ssize_t hmcdrv_dev_write(struct file *fp, const char __user *ubuf,
size_t len, loff_t *pos)
{
ssize_t retlen;
void *pdata;
pr_debug("writing file '/dev/%pD' at pos. %lld with length %zd\n",
fp, (long long) *pos, len);
if (!fp->private_data) { /* first expect a cmd write */
fp->private_data = kmalloc(len + 1, GFP_KERNEL);
if (!fp->private_data)
return -ENOMEM;
if (!copy_from_user(fp->private_data, ubuf, len)) {
((char *)fp->private_data)[len] = '\0';
return len;
}
kfree(fp->private_data);
fp->private_data = NULL;
return -EFAULT;
pdata = memdup_user_nul(ubuf, len);
if (IS_ERR(pdata))
return PTR_ERR(pdata);
fp->private_data = pdata;
return len;
}
retlen = hmcdrv_dev_transfer((char *) fp->private_data,