From: Xiang Mei When batching multiple NFLOG messages (inst->qlen > 1), __nfulnl_send() appends an NLMSG_DONE terminator with sizeof(struct nfgenmsg) payload via nlmsg_put(), but never initializes the nfgenmsg bytes. The nlmsg_put() helper only zeroes alignment padding after the payload, not the payload itself, so four bytes of stale kernel heap data are leaked to userspace in the NLMSG_DONE message body. Use nfnl_msg_put() to build the NLMSG_DONE terminator, which initializes the nfgenmsg payload via nfnl_fill_hdr(), consistent with how __build_packet_message() already constructs NFULNL_MSG_PACKET headers. Fixes: 29c5d4afba51 ("[NETFILTER]: nfnetlink_log: fix sending of multipart messages") Reported-by: Weiming Shi Signed-off-by: Xiang Mei Signed-off-by: Florian Westphal --- net/netfilter/nfnetlink_log.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c index f80978c06fa0..0db908518b2f 100644 --- a/net/netfilter/nfnetlink_log.c +++ b/net/netfilter/nfnetlink_log.c @@ -361,10 +361,10 @@ static void __nfulnl_send(struct nfulnl_instance *inst) { if (inst->qlen > 1) { - struct nlmsghdr *nlh = nlmsg_put(inst->skb, 0, 0, - NLMSG_DONE, - sizeof(struct nfgenmsg), - 0); + struct nlmsghdr *nlh = nfnl_msg_put(inst->skb, 0, 0, + NLMSG_DONE, 0, + AF_UNSPEC, NFNETLINK_V0, + htons(inst->group_num)); if (WARN_ONCE(!nlh, "bad nlskb size: %u, tailroom %d\n", inst->skb->len, skb_tailroom(inst->skb))) { kfree_skb(inst->skb); -- 2.52.0