[PATCH] nfc/nci: Add the inconsistency check between the input data length and count

[Edward Adam Davis]

write$nci(r0, &(0x7f0000000740)=ANY=[@ANYBLOB="610501"], 0xf)

Syzbot constructed a write() call with a data length of 3 bytes but a count value
of 15, which passed too little data to meet the basic requirements of the function
nci_rf_intf_activated_ntf_packet().

Therefore, increasing the comparison between data length and count value to avoid
problems caused by inconsistent data length and count.

Reported-and-tested-by: syzbot+71bfed2b2bcea46c98f2@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
---
 drivers/nfc/virtual_ncidev.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/nfc/virtual_ncidev.c b/drivers/nfc/virtual_ncidev.c
index 590b038e449e..6b89d596ba9a 100644
--- a/drivers/nfc/virtual_ncidev.c
+++ b/drivers/nfc/virtual_ncidev.c
@@ -125,6 +125,10 @@ 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;
-- 
2.43.0