Commit 4843b93c authored Mar 03, 2009 by Pablo Neira Ayuso Committed by David S. Miller Mar 03, 2009

netlink: invert error code in netlink_set_err()



The callers of netlink_set_err() currently pass a negative value
as parameter for the error code. However, sk->sk_err wants a
positive error value. Without this patch, skb_recv_datagram() called
by netlink_recvmsg() may return a positive value to report an error.

Another choice to fix this is to change callers to pass a positive
error value, but this seems a bit inconsistent and error prone
to me. Indeed, the callers of netlink_set_err() assumed that the
(usual) negative value for error codes was fine before this patch :).

This patch also includes some documentation in docbook format
for netlink_set_err() to avoid this sort of confusion.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 17edde52

net/netlink/af_netlink.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -1084,6 +1084,13 @@ static inline int do_one_set_err(struct sock *sk,
		return 0;
		}

		/**
		* netlink_set_err - report error to broadcast listeners
		* @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
		* @pid: the PID of a process that we want to skip (if any)
		* @groups: the broadcast group that will notice the error
		* @code: error code, must be negative (as usual in kernelspace)
		*/
		void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
		{
		struct netlink_set_err_data info;
		@@ -1093,7 +1100,8 @@ void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
		info.exclude_sk = ssk;
		info.pid = pid;
		info.group = group;
		info.code = code;
		/* sk->sk_err wants a positive error value */
		info.code = -code;

		read_lock(&nl_table_lock);