From aa3a022094fac7f6e48050e139fa8a5a2e3265ce Mon Sep 17 00:00:00 2001 From: Ken-ichirou MATSUZAWA Date: Fri, 29 Jan 2016 10:45:50 +0900 Subject: [PATCH] netlink: not trim skb for mmaped socket when dump We should not trim skb for mmaped socket since its buf size is fixed and userspace will read as frame which data equals head. mmaped socket will not call recvmsg, means max_recvmsg_len is 0, skb_reserve was not called before commit: db65a3aaf29e. Fixes: db65a3aaf29e (netlink: Trim skb to alloc size to avoid MSG_TRUNC) Signed-off-by: Ken-ichirou MATSUZAWA Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 81dc1bb6e016..f1ffb34e253f 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2831,7 +2831,8 @@ static int netlink_dump(struct sock *sk) * reasonable static buffer based on the expected largest dump of a * single netdev. The outcome is MSG_TRUNC error. */ - skb_reserve(skb, skb_tailroom(skb) - alloc_size); + if (!netlink_rx_is_mmaped(sk)) + skb_reserve(skb, skb_tailroom(skb) - alloc_size); netlink_skb_set_owner_r(skb, sk); len = cb->dump(skb, cb); -- 2.20.1