Code: static void llc_cmsg_rcv(struct msghdr *msg, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(skb->sk);

 	if (llc->cmsg_flags & LLC_CMSG_PKTINFO) {
 		struct llc_pktinfo info;
 
 		info.lpi_ifindex = llc_sk(skb->sk)->dev->ifindex;
 		llc_pdu_decode_dsap(skb, &info.lpi_sap);
 		llc_pdu_decode_da(skb, info.lpi_mac);
		put_cmsg(msg, SOL_LLC, LLC_OPT_PKTINFO, sizeof(info), &info);
	}
}

Vulnerability Type: +Info 
CWE ID: CWE-200
Summary: The llc_cmsg_rcv function in net/llc/af_llc.c in the Linux kernel before 4.5.5 does not initialize a certain data structure, which allows attackers to obtain sensitive information from kernel stack memory by reading a message.
Commit Message: net: fix infoleak in llc

The stack object “info” has a total size of 12 bytes. Its last byte
is padding which is not initialized and leaked via “put_cmsg”.

Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>