From: Willem de Bruijn
> Sent: 26 April 2019 20:28
> Packet sockets in datagram mode take a destination address. Verify its
> length before passing to dev_hard_header.
>
> Prior to 2.6.14-rc3, the send code ignored sll_halen. This is
> established behavior. Directly compare msg_namelen to dev->addr_len.
>
> Fixes: 6b8d95f1795c4 ("packet: validate address length if non-zero")
> Suggested-by: David Laight <david.lai...@aculab.com>
> Signed-off-by: Willem de Bruijn <will...@google.com>
> ---
> net/packet/af_packet.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index 9419c5cf4de5e..13301e36b4a28 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -2624,10 +2624,13 @@ static int tpacket_snd(struct packet_sock *po, struct
> msghdr *msg)
> sll_addr)))
> goto out;
> proto = saddr->sll_protocol;
> - addr = saddr->sll_halen ? saddr->sll_addr : NULL;
> dev = dev_get_by_index(sock_net(&po->sk), saddr->sll_ifindex);
> - if (addr && dev && saddr->sll_halen < dev->addr_len)
> - goto out_put;
> + if (po->sk.sk_socket->type == SOCK_DGRAM) {
> + addr = saddr->sll_addr;
> + if (dev && msg->msg_namelen < dev->addr_len +
> + offsetof(struct sockaddr_ll, sll_addr))
> + goto out_put;
> + }
IIRC you need to initialise 'addr - NULL' at the top of the functions.
I'm surprised the compiler doesn't complain.
David
-
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