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packet: round up linear to header len

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commit 57031eb794906eea4e1c7b31dc1e2429c0af0c66 upstream.

Link layer protocols may unconditionally pull headers, as Ethernet
does in eth_type_trans. Ensure that the entire link layer header
always lies in the skb linear segment. tpacket_snd has such a check.
Extend this to packet_snd.

Variable length link layer headers complicate the computation
somewhat. Here skb->len may be smaller than dev->hard_header_len.

Round up the linear length to be at least as long as the smallest of
the two.

[js] no virtio helpers in 3.12

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>
This commit is contained in:
Willem de Bruijn
2017-02-07 15:57:21 -05:00
committed by Willy Tarreau
parent b0899f8009
commit c6cc07d404
1 changed files with 4 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/packet/af_packet.c
+4 -2
View File
@@ -2242,7 +2242,7 @@ static int packet_snd(struct socket *sock,
int vnet_hdr_len;
struct packet_sock *po = pkt_sk(sk);
unsigned short gso_type = 0;
int hlen, tlen;
int hlen, tlen, linear;
int extra_len = 0;
/*
@@ -2336,7 +2336,9 @@ static int packet_snd(struct socket *sock,
err = -ENOBUFS;
hlen = LL_RESERVED_SPACE(dev);
tlen = dev->needed_tailroom;
skb = packet_alloc_skb(sk, hlen + tlen, hlen, len, vnet_hdr.hdr_len,
linear = vnet_hdr.hdr_len;
linear = max(linear, min_t(int, len, dev->hard_header_len));
skb = packet_alloc_skb(sk, hlen + tlen, hlen, len, linear,
msg->msg_flags & MSG_DONTWAIT, &err);
if (skb == NULL)
goto out_unlock;