Revert "nfc/nci: Add the inconsistency check between the input data length and count"

This reverts commit 068648a.

NFC packets may have NUL-bytes. Checking for string length is not a correct
assumption here. As long as there is a check for the length copied from
copy_from_user, all should be fine.

The fix only prevented the syzbot reproducer from triggering the bug
because the packet is not enqueued anymore and the code that triggers the
bug is not exercised.

The fix even broke
testing/selftests/nci/nci_dev, making all tests there fail. After the
revert, 6 out of 8 tests pass.

Fixes: 068648a ("nfc/nci: Add the inconsistency check between the input data length and count")
Cc: stable@vger.kernel.org
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Link: https://patch.msgid.link/20260113202458.449455-1-cascardo@igalia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Thadeu Lima de Souza Cascardo

drivers/nfc/virtual_ncidev.c

@@ -125,10 +125,6 @@ static ssize_t virtual_ncidev_write(struct file *file,
 		kfree_skb(skb);
 		return -EFAULT;
 	}
-	if (strnlen(skb->data, count) != count) {
-		kfree_skb(skb);
-		return -EINVAL;
-	}
 
 	nci_recv_frame(vdev->ndev, skb);
 	return count;