[PPP] generic: Call skb_cow_head before scribbling over skb

[mirror_ubuntu-bionic-kernel.git] / drivers / net / ppp_generic.c

diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index ef3325b692335312f176aa3a86275ffcc5e6bad7..7e21342becb2eb00175613622649ec9ff7545c4c 100644 (file)
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -899,17 +899,9 @@ ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
        /* Put the 2-byte PPP protocol number on the front,
           making sure there is room for the address and control fields. */
-       if (skb_headroom(skb) < PPP_HDRLEN) {
-               struct sk_buff *ns;
-
-               ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
-               if (ns == 0)
-                       goto outf;
-               skb_reserve(ns, dev->hard_header_len);
-               skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
-               kfree_skb(skb);
-               skb = ns;
-       }
+       if (skb_cow_head(skb, PPP_HDRLEN))
+               goto outf;
+
        pp = skb_push(skb, 2);
        proto = npindex_to_proto[npi];
        pp[0] = proto >> 8;
@@ -1726,7 +1718,7 @@ ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
                }
                /* the decompressor still expects the A/C bytes in the hdr */
                len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
-                               skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
+                               skb->len + 2, ns->data, obuff_size);
                if (len < 0) {
                        /* Pass the compressed frame to pppd as an
                           error indication. */