From: Michal Kubecek <[email protected]> 3.12-stable review patch. If anyone has any objections, please let me know.
=============== commit 21ee543edc0dea36ab58d24523fcd42b8a270df8 upstream. The xfrm_user module registers its pernet init/exit after xfrm itself so that its net exit function xfrm_user_net_exit() is executed before xfrm_net_exit() which calls xfrm_state_fini() to cleanup the SA's (xfrm states). This opens a window between zeroing net->xfrm.nlsk pointer and deleting all xfrm_state instances which may access it (via the timer). If an xfrm state expires in this window, xfrm_exp_state_notify() will pass null pointer as socket to nlmsg_multicast(). As the notifications are called inside rcu_read_lock() block, it is sufficient to retrieve the nlsk socket with rcu_dereference() and check the it for null. Signed-off-by: Michal Kubecek <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Jiri Slaby <[email protected]> --- net/xfrm/xfrm_user.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 352dfa4c39ee..32a2dd39b785 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -930,6 +930,20 @@ static struct sk_buff *xfrm_state_netlink(struct sk_buff *in_skb, return skb; } +/* A wrapper for nlmsg_multicast() checking that nlsk is still available. + * Must be called with RCU read lock. + */ +static inline int xfrm_nlmsg_multicast(struct net *net, struct sk_buff *skb, + u32 pid, unsigned int group) +{ + struct sock *nlsk = rcu_dereference(net->xfrm.nlsk); + + if (nlsk) + return nlmsg_multicast(nlsk, skb, pid, group, GFP_ATOMIC); + else + return -1; +} + static inline size_t xfrm_spdinfo_msgsize(void) { return NLMSG_ALIGN(4) @@ -2253,7 +2267,7 @@ static int xfrm_send_migrate(const struct xfrm_selector *sel, u8 dir, u8 type, if (build_migrate(skb, m, num_migrate, k, sel, dir, type) < 0) BUG(); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_MIGRATE, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_MIGRATE); } #else static int xfrm_send_migrate(const struct xfrm_selector *sel, u8 dir, u8 type, @@ -2440,7 +2454,7 @@ static int xfrm_exp_state_notify(struct xfrm_state *x, const struct km_event *c) return -EMSGSIZE; } - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_EXPIRE, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_EXPIRE); } static int xfrm_aevent_state_notify(struct xfrm_state *x, const struct km_event *c) @@ -2455,7 +2469,7 @@ static int xfrm_aevent_state_notify(struct xfrm_state *x, const struct km_event if (build_aevent(skb, x, c) < 0) BUG(); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_AEVENTS, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_AEVENTS); } static int xfrm_notify_sa_flush(const struct km_event *c) @@ -2481,7 +2495,7 @@ static int xfrm_notify_sa_flush(const struct km_event *c) nlmsg_end(skb, nlh); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_SA, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_SA); } static inline size_t xfrm_sa_len(struct xfrm_state *x) @@ -2568,7 +2582,7 @@ static int xfrm_notify_sa(struct xfrm_state *x, const struct km_event *c) nlmsg_end(skb, nlh); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_SA, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_SA); out_free_skb: kfree_skb(skb); @@ -2659,7 +2673,7 @@ static int xfrm_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *xt, if (build_acquire(skb, x, xt, xp) < 0) BUG(); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_ACQUIRE, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_ACQUIRE); } /* User gives us xfrm_user_policy_info followed by an array of 0 @@ -2773,7 +2787,7 @@ static int xfrm_exp_policy_notify(struct xfrm_policy *xp, int dir, const struct if (build_polexpire(skb, xp, dir, c) < 0) BUG(); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_EXPIRE, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_EXPIRE); } static int xfrm_notify_policy(struct xfrm_policy *xp, int dir, const struct km_event *c) @@ -2835,7 +2849,7 @@ static int xfrm_notify_policy(struct xfrm_policy *xp, int dir, const struct km_e nlmsg_end(skb, nlh); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_POLICY, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_POLICY); out_free_skb: kfree_skb(skb); @@ -2863,7 +2877,7 @@ static int xfrm_notify_policy_flush(const struct km_event *c) nlmsg_end(skb, nlh); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_POLICY, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_POLICY); out_free_skb: kfree_skb(skb); @@ -2932,7 +2946,7 @@ static int xfrm_send_report(struct net *net, u8 proto, if (build_report(skb, proto, sel, addr) < 0) BUG(); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_REPORT, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_REPORT); } static inline size_t xfrm_mapping_msgsize(void) @@ -2984,7 +2998,7 @@ static int xfrm_send_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, if (build_mapping(skb, x, ipaddr, sport) < 0) BUG(); - return nlmsg_multicast(net->xfrm.nlsk, skb, 0, XFRMNLGRP_MAPPING, GFP_ATOMIC); + return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_MAPPING); } static struct xfrm_mgr netlink_mgr = { -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
