thunderbolt: Fix NULL dereference in tb_remove_work()grafted

There is a slight race between tb_remove_work() and tb_domain_remove()
which leads to dereferencing a NULL tb->root_switch pointer inside
tb_free_unplugged_xdomains():

        Thread A                            Thread B

  tb_remove_work()
                                    tb_domain_remove()
                                      mutex_lock(&tb->lock)
                                      tb_stop()
                                        /* doesn't cancel a running callback */
                                        cancel_delayed_work(&tcm->remove_work)
                                        ...
                                        tb_switch_remove(tb->root_switch)
                                        tb->root_switch = NULL
                                      mutex_unlock(&tb->lock)
    mutex_lock(&tb->lock)
    ...
    /* without checking ->root_switch */
    tb_free_unplugged_xdomains(tb->root_switch)
    mutex_unlock(&tb->lock)

Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without
holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains()
out of the &tb->lock section and the check for tb->root_switch, in
particular.  It states:

  For this reason separate removing the XDomain from the topology data
  structures (where we need the lock) from unregistering the device from
  the bus (where remove callbacks of the drivers are being called).

tb_free_unplugged_xdomains() belongs to the former group of functions
requiring the lock.  And it also calls tb_xdomain_remove() which should
only be called with &tb->lock held.

Found by Linux Verification Center (linuxtesting.org) with Svace static
analysis tool.

Fixes: a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 269 insertions, 0 deletions

diff --git a/include/net/tc_wrapper.h b/include/net/tc_wrapper.h
new file mode 100644
index 000000000..4ebb053bb
--- /dev/null
+++ b/include/net/tc_wrapper.h
@@ -0,0 +1,269 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_TC_WRAPPER_H
+#define __NET_TC_WRAPPER_H
+
+#include <net/pkt_cls.h>
+
+#if IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)
+
+#include <linux/cpufeature.h>
+#include <linux/static_key.h>
+#include <linux/indirect_call_wrapper.h>
+
+#define TC_INDIRECT_SCOPE
+
+extern struct static_key_false tc_skip_wrapper_act;
+extern struct static_key_false tc_skip_wrapper_cls;
+
+/* TC Actions */
+#ifdef CONFIG_NET_CLS_ACT
+
+#define TC_INDIRECT_ACTION_DECLARE(fname)                              \
+	INDIRECT_CALLABLE_DECLARE(int fname(struct sk_buff *skb,       \
+					    const struct tc_action *a, \
+					    struct tcf_result *res))
+
+TC_INDIRECT_ACTION_DECLARE(tcf_bpf_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_connmark_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_csum_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_ct_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_ctinfo_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_gact_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_gate_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_ife_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_ipt_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_mirred_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_mpls_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_nat_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_pedit_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_police_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_sample_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_simp_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_skbedit_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_skbmod_act);
+TC_INDIRECT_ACTION_DECLARE(tcf_vlan_act);
+TC_INDIRECT_ACTION_DECLARE(tunnel_key_act);
+
+static inline int tc_act(struct sk_buff *skb, const struct tc_action *a,
+			   struct tcf_result *res)
+{
+	if (static_branch_likely(&tc_skip_wrapper_act))
+		goto skip;
+
+#if IS_BUILTIN(CONFIG_NET_ACT_GACT)
+	if (a->ops->act == tcf_gact_act)
+		return tcf_gact_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_MIRRED)
+	if (a->ops->act == tcf_mirred_act)
+		return tcf_mirred_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_PEDIT)
+	if (a->ops->act == tcf_pedit_act)
+		return tcf_pedit_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_SKBEDIT)
+	if (a->ops->act == tcf_skbedit_act)
+		return tcf_skbedit_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_SKBMOD)
+	if (a->ops->act == tcf_skbmod_act)
+		return tcf_skbmod_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_POLICE)
+	if (a->ops->act == tcf_police_act)
+		return tcf_police_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_BPF)
+	if (a->ops->act == tcf_bpf_act)
+		return tcf_bpf_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_CONNMARK)
+	if (a->ops->act == tcf_connmark_act)
+		return tcf_connmark_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_CSUM)
+	if (a->ops->act == tcf_csum_act)
+		return tcf_csum_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_CT)
+	if (a->ops->act == tcf_ct_act)
+		return tcf_ct_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_CTINFO)
+	if (a->ops->act == tcf_ctinfo_act)
+		return tcf_ctinfo_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_GATE)
+	if (a->ops->act == tcf_gate_act)
+		return tcf_gate_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_MPLS)
+	if (a->ops->act == tcf_mpls_act)
+		return tcf_mpls_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_NAT)
+	if (a->ops->act == tcf_nat_act)
+		return tcf_nat_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_TUNNEL_KEY)
+	if (a->ops->act == tunnel_key_act)
+		return tunnel_key_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_VLAN)
+	if (a->ops->act == tcf_vlan_act)
+		return tcf_vlan_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_IFE)
+	if (a->ops->act == tcf_ife_act)
+		return tcf_ife_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_SIMP)
+	if (a->ops->act == tcf_simp_act)
+		return tcf_simp_act(skb, a, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_ACT_SAMPLE)
+	if (a->ops->act == tcf_sample_act)
+		return tcf_sample_act(skb, a, res);
+#endif
+
+skip:
+	return a->ops->act(skb, a, res);
+}
+
+#endif /* CONFIG_NET_CLS_ACT */
+
+/* TC Filters */
+#ifdef CONFIG_NET_CLS
+
+#define TC_INDIRECT_FILTER_DECLARE(fname)                               \
+	INDIRECT_CALLABLE_DECLARE(int fname(struct sk_buff *skb,        \
+					    const struct tcf_proto *tp, \
+					    struct tcf_result *res))
+
+TC_INDIRECT_FILTER_DECLARE(basic_classify);
+TC_INDIRECT_FILTER_DECLARE(cls_bpf_classify);
+TC_INDIRECT_FILTER_DECLARE(cls_cgroup_classify);
+TC_INDIRECT_FILTER_DECLARE(fl_classify);
+TC_INDIRECT_FILTER_DECLARE(flow_classify);
+TC_INDIRECT_FILTER_DECLARE(fw_classify);
+TC_INDIRECT_FILTER_DECLARE(mall_classify);
+TC_INDIRECT_FILTER_DECLARE(route4_classify);
+TC_INDIRECT_FILTER_DECLARE(u32_classify);
+
+static inline int tc_classify(struct sk_buff *skb, const struct tcf_proto *tp,
+				struct tcf_result *res)
+{
+	if (static_branch_likely(&tc_skip_wrapper_cls))
+		goto skip;
+
+#if IS_BUILTIN(CONFIG_NET_CLS_BPF)
+	if (tp->classify == cls_bpf_classify)
+		return cls_bpf_classify(skb, tp, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_CLS_U32)
+	if (tp->classify == u32_classify)
+		return u32_classify(skb, tp, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_CLS_FLOWER)
+	if (tp->classify == fl_classify)
+		return fl_classify(skb, tp, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_CLS_FW)
+	if (tp->classify == fw_classify)
+		return fw_classify(skb, tp, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_CLS_MATCHALL)
+	if (tp->classify == mall_classify)
+		return mall_classify(skb, tp, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_CLS_BASIC)
+	if (tp->classify == basic_classify)
+		return basic_classify(skb, tp, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_CLS_CGROUP)
+	if (tp->classify == cls_cgroup_classify)
+		return cls_cgroup_classify(skb, tp, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_CLS_FLOW)
+	if (tp->classify == flow_classify)
+		return flow_classify(skb, tp, res);
+#endif
+#if IS_BUILTIN(CONFIG_NET_CLS_ROUTE4)
+	if (tp->classify == route4_classify)
+		return route4_classify(skb, tp, res);
+#endif
+
+skip:
+	return tp->classify(skb, tp, res);
+}
+
+#endif /* CONFIG_NET_CLS */
+
+static inline void tc_wrapper_init(void)
+{
+#ifdef CONFIG_X86
+	int cnt_cls = IS_BUILTIN(CONFIG_NET_CLS_BPF) +
+		IS_BUILTIN(CONFIG_NET_CLS_U32)  +
+		IS_BUILTIN(CONFIG_NET_CLS_FLOWER) +
+		IS_BUILTIN(CONFIG_NET_CLS_FW) +
+		IS_BUILTIN(CONFIG_NET_CLS_MATCHALL) +
+		IS_BUILTIN(CONFIG_NET_CLS_BASIC) +
+		IS_BUILTIN(CONFIG_NET_CLS_CGROUP) +
+		IS_BUILTIN(CONFIG_NET_CLS_FLOW) +
+		IS_BUILTIN(CONFIG_NET_CLS_ROUTE4);
+
+	int cnt_act = IS_BUILTIN(CONFIG_NET_ACT_GACT) +
+		IS_BUILTIN(CONFIG_NET_ACT_MIRRED) +
+		IS_BUILTIN(CONFIG_NET_ACT_PEDIT) +
+		IS_BUILTIN(CONFIG_NET_ACT_SKBEDIT) +
+		IS_BUILTIN(CONFIG_NET_ACT_SKBMOD) +
+		IS_BUILTIN(CONFIG_NET_ACT_POLICE) +
+		IS_BUILTIN(CONFIG_NET_ACT_BPF) +
+		IS_BUILTIN(CONFIG_NET_ACT_CONNMARK) +
+		IS_BUILTIN(CONFIG_NET_ACT_CSUM) +
+		IS_BUILTIN(CONFIG_NET_ACT_CT) +
+		IS_BUILTIN(CONFIG_NET_ACT_CTINFO) +
+		IS_BUILTIN(CONFIG_NET_ACT_GATE) +
+		IS_BUILTIN(CONFIG_NET_ACT_MPLS) +
+		IS_BUILTIN(CONFIG_NET_ACT_NAT) +
+		IS_BUILTIN(CONFIG_NET_ACT_TUNNEL_KEY) +
+		IS_BUILTIN(CONFIG_NET_ACT_VLAN) +
+		IS_BUILTIN(CONFIG_NET_ACT_IFE) +
+		IS_BUILTIN(CONFIG_NET_ACT_SIMP) +
+		IS_BUILTIN(CONFIG_NET_ACT_SAMPLE);
+
+	if (cpu_feature_enabled(X86_FEATURE_RETPOLINE))
+		return;
+
+	if (cnt_cls > 1)
+		static_branch_enable(&tc_skip_wrapper_cls);
+
+	if (cnt_act > 1)
+		static_branch_enable(&tc_skip_wrapper_act);
+#endif
+}
+
+#else
+
+#define TC_INDIRECT_SCOPE static
+
+static inline int tc_act(struct sk_buff *skb, const struct tc_action *a,
+			   struct tcf_result *res)
+{
+	return a->ops->act(skb, a, res);
+}
+
+static inline int tc_classify(struct sk_buff *skb, const struct tcf_proto *tp,
+				struct tcf_result *res)
+{
+	return tp->classify(skb, tp, res);
+}
+
+static inline void tc_wrapper_init(void)
+{
+}
+
+#endif
+
+#endif /* __NET_TC_WRAPPER_H */