From: Xie He Date: Sat, 31 Oct 2020 18:10:42 +0000 (-0700) Subject: net: hdlc_fr: Improve the initial checks when we receive an skb X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=77124c4463d45083e69b7284415467737f31f76b;p=linux.git net: hdlc_fr: Improve the initial checks when we receive an skb 1. Change the skb->len check from "<= 4" to "< 4". At first we only need to ensure a 4-byte header is present. We indeed normally need the 5th byte, too, but it'd be more logical and cleaner to check its existence when we actually need it. 2. Add an fh->ea2 check to the initial checks in fr_rx. fh->ea2 == 1 means the second address byte is the final address byte. We only support the case where the address length is 2 bytes. Cc: Krzysztof Halasa Signed-off-by: Xie He Acked-by: Willem de Bruijn Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c index eb83116aa9df7..98444f1d8cc30 100644 --- a/drivers/net/wan/hdlc_fr.c +++ b/drivers/net/wan/hdlc_fr.c @@ -882,7 +882,7 @@ static int fr_rx(struct sk_buff *skb) struct pvc_device *pvc; struct net_device *dev; - if (skb->len <= 4 || fh->ea1 || data[2] != FR_UI) + if (skb->len < 4 || fh->ea1 || !fh->ea2 || data[2] != FR_UI) goto rx_error; dlci = q922_to_dlci(skb->data);