Re: git: f5a365e51fee - main - inet6: protect address manipulation with a lock

  Mateusz,

On Thu, Mar 30, 2023 at 08:47:01AM +0000, Mateusz Guzik wrote:
M> diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
M> index 27dc3550177c..3d967e9a40c7 100644
M> --- a/sys/netinet6/in6.c
M> +++ b/sys/netinet6/in6.c
M> @@ -168,6 +168,9 @@ static void in6_leave_proxy_ndp_mc(struct ifnet *, const struct in6_addr *);
M>  #define ifa2ia6(ifa)	((struct in6_ifaddr *)(ifa))
M>  #define ia62ifa(ia6)	(&((ia6)->ia_ifa))
M>  
M> +static struct sx in6_control_sx;
M> +SX_SYSINIT(in6_control_sx, &in6_control_sx, "in6_control");
M> +
M>  void
M>  in6_newaddrmsg(struct in6_ifaddr *ia, int cmd)
M>  {
M> @@ -254,6 +257,7 @@ in6_control(struct socket *so, u_long cmd, void *data,
M>  	struct	in6_aliasreq *ifra = (struct in6_aliasreq *)data;
M>  	struct sockaddr_in6 *sa6;
M>  	int error;
M> +	bool control_locked = false;
M>  
M>  	/*
M>  	 * Compat to make pre-10.x ifconfig(8) operable.
M> @@ -411,6 +415,8 @@ in6_control(struct socket *so, u_long cmd, void *data,
M>  		if (td != NULL && (error = prison_check_ip6(td->td_ucred,
M>  		    &sa6->sin6_addr)) != 0)
M>  			return (error);
M> +		sx_xlock(&in6_control_sx);
M> +		control_locked = true;
M>  		ia = in6ifa_ifpwithaddr(ifp, &sa6->sin6_addr);
M>  	} else
M>  		ia = NULL;
M> @@ -582,6 +588,9 @@ in6_control(struct socket *so, u_long cmd, void *data,
M>  
M>  	error = 0;
M>  out:
M> +	if (control_locked)
M> +		sx_xunlock(&in6_control_sx);
M> +
M>  	if (ia != NULL)
M>  		ifa_free(&ia->ia_ifa);
M>  	return (error);

Why do you prefer a bool over using sx_xlocked()?

-- 
Gleb Smirnoff