From: Thadeu Lima de Souza Cascardo Date: Tue, 13 Jan 2026 20:24:58 +0000 (-0300) Subject: Revert "nfc/nci: Add the inconsistency check between the input data length and count" X-Git-Tag: v6.6.122~116 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=93cbf6d80da2aaecabc5dd0b6745894b25238217;p=thirdparty%2Fkernel%2Fstable.git Revert "nfc/nci: Add the inconsistency check between the input data length and count" commit f40ddcc0c0ca1a0122a7f4440b429f97d5832bdf upstream. This reverts commit 068648aab72c9ba7b0597354ef4d81ffaac7b979. 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: 068648aab72c ("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 Link: https://patch.msgid.link/20260113202458.449455-1-cascardo@igalia.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/nfc/virtual_ncidev.c b/drivers/nfc/virtual_ncidev.c index 6b89d596ba9af..590b038e449e5 100644 --- a/drivers/nfc/virtual_ncidev.c +++ b/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;