From: Willem de Bruijn
> Sent: 29 April 2019 16:47
> Packet send checks that msg_name is at least sizeof sockaddr_ll.
> Packet recv must return at least this length, so that its output
> can be passed unmodified to packet send.
>
> This ceased to be true since adding support for lladdr longer than
> sll_addr. Since, the return value uses true address length.
>
> Always return at least sizeof sockaddr_ll, even if address length
> is shorter. Zero the padding bytes.
>
> Change v1->v2: do not overwrite zeroed padding again. use copy_len.
>
> Fixes: 0fb375fb9b93 ("[AF_PACKET]: Allow for > 8 byte hardware addresses.")
> Suggested-by: David Laight <david.lai...@aculab.com>
> Signed-off-by: Willem de Bruijn <will...@google.com>
> ---
> net/packet/af_packet.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index e726aaba73b9f..5fe3d75b6212d 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -3348,20 +3348,29 @@ static int packet_recvmsg(struct socket *sock, struct
> msghdr *msg, size_t len,
> sock_recv_ts_and_drops(msg, sk, skb);
>
> if (msg->msg_name) {
> + int copy_len;
> +
> /* If the address length field is there to be filled
> * in, we fill it in now.
> */
> if (sock->type == SOCK_PACKET) {
> __sockaddr_check_size(sizeof(struct sockaddr_pkt));
> msg->msg_namelen = sizeof(struct sockaddr_pkt);
> + copy_len = msg->msg_namelen;
> } else {
> struct sockaddr_ll *sll = &PACKET_SKB_CB(skb)->sa.ll;
>
> msg->msg_namelen = sll->sll_halen +
> offsetof(struct sockaddr_ll, sll_addr);
> + copy_len = msg->msg_namelen;
> + if (msg->msg_namelen < sizeof(struct sockaddr_ll)) {
> + memset(msg->msg_name +
> + offsetof(struct sockaddr_ll, sll_addr),
> + 0, sizeof(sll->sll_addr));
> + msg->msg_namelen = sizeof(struct sockaddr_ll);
> + }
> }
> - memcpy(msg->msg_name, &PACKET_SKB_CB(skb)->sa,
> - msg->msg_namelen);
> + memcpy(msg->msg_name, &PACKET_SKB_CB(skb)->sa, copy_len);
> }
>
> if (pkt_sk(sk)->auxdata) {
> --
> 2.21.0.593.g511ec345e18-goog
Looks ok to me, not tried to compile it though.
David
-
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