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, 174 insertions, 0 deletions

diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
new file mode 100644
index 000000000..b2ba5a805
--- /dev/null
+++ b/include/trace/define_trace.h
@@ -0,0 +1,174 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Trace files that want to automate creation of all tracepoints defined
+ * in their file should include this file. The following are macros that the
+ * trace file may define:
+ *
+ * TRACE_SYSTEM defines the system the tracepoint is for
+ *
+ * TRACE_INCLUDE_FILE if the file name is something other than TRACE_SYSTEM.h
+ *     This macro may be defined to tell define_trace.h what file to include.
+ *     Note, leave off the ".h".
+ *
+ * TRACE_INCLUDE_PATH if the path is something other than core kernel include/trace
+ *     then this macro can define the path to use. Note, the path is relative to
+ *     define_trace.h, not the file including it. Full path names for out of tree
+ *     modules must be used.
+ */
+
+#ifdef CREATE_TRACE_POINTS
+
+/* Prevent recursion */
+#undef CREATE_TRACE_POINTS
+
+#include <linux/stringify.h>
+
+#undef TRACE_EVENT
+#define TRACE_EVENT(name, proto, args, tstruct, assign, print)	\
+	DEFINE_TRACE(name, PARAMS(proto), PARAMS(args))
+
+#undef TRACE_EVENT_CONDITION
+#define TRACE_EVENT_CONDITION(name, proto, args, cond, tstruct, assign, print) \
+	TRACE_EVENT(name,						\
+		PARAMS(proto),						\
+		PARAMS(args),						\
+		PARAMS(tstruct),					\
+		PARAMS(assign),						\
+		PARAMS(print))
+
+#undef TRACE_EVENT_FN
+#define TRACE_EVENT_FN(name, proto, args, tstruct,		\
+		assign, print, reg, unreg)			\
+	DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args))
+
+#undef TRACE_EVENT_FN_COND
+#define TRACE_EVENT_FN_COND(name, proto, args, cond, tstruct,		\
+		assign, print, reg, unreg)			\
+	DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args))
+
+#undef TRACE_EVENT_SYSCALL
+#define TRACE_EVENT_SYSCALL(name, proto, args, struct, assign, print, reg, unreg) \
+	DEFINE_TRACE_SYSCALL(name, reg, unreg, PARAMS(proto), PARAMS(args))
+
+#undef TRACE_EVENT_NOP
+#define TRACE_EVENT_NOP(name, proto, args, struct, assign, print)
+
+#undef DEFINE_EVENT_NOP
+#define DEFINE_EVENT_NOP(template, name, proto, args)
+
+#undef DEFINE_EVENT
+#define DEFINE_EVENT(template, name, proto, args) \
+	DEFINE_TRACE(name, PARAMS(proto), PARAMS(args))
+
+#undef DEFINE_EVENT_FN
+#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg) \
+	DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args))
+
+#undef DEFINE_EVENT_PRINT
+#define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\
+	DEFINE_TRACE(name, PARAMS(proto), PARAMS(args))
+
+#undef DEFINE_EVENT_CONDITION
+#define DEFINE_EVENT_CONDITION(template, name, proto, args, cond) \
+	DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))
+
+#undef DECLARE_TRACE
+#define DECLARE_TRACE(name, proto, args)	\
+	DEFINE_TRACE(name##_tp, PARAMS(proto), PARAMS(args))
+
+#undef DECLARE_TRACE_CONDITION
+#define DECLARE_TRACE_CONDITION(name, proto, args, cond)	\
+	DEFINE_TRACE(name##_tp, PARAMS(proto), PARAMS(args))
+
+#undef DECLARE_TRACE_EVENT
+#define DECLARE_TRACE_EVENT(name, proto, args)	\
+	DEFINE_TRACE(name, PARAMS(proto), PARAMS(args))
+
+#undef DECLARE_TRACE_EVENT_CONDITION
+#define DECLARE_TRACE_EVENT_CONDITION(name, proto, args, cond)	\
+	DEFINE_TRACE(name, PARAMS(proto), PARAMS(args))
+
+/* If requested, create helpers for calling these tracepoints from Rust. */
+#ifdef CREATE_RUST_TRACE_POINTS
+#undef DEFINE_RUST_DO_TRACE
+#define DEFINE_RUST_DO_TRACE(name, proto, args)	\
+	__DEFINE_RUST_DO_TRACE(name, PARAMS(proto), PARAMS(args))
+#endif
+
+#undef TRACE_INCLUDE
+#undef __TRACE_INCLUDE
+
+#ifndef TRACE_INCLUDE_FILE
+# define TRACE_INCLUDE_FILE TRACE_SYSTEM
+# define UNDEF_TRACE_INCLUDE_FILE
+#endif
+
+#ifndef TRACE_INCLUDE_PATH
+# define __TRACE_INCLUDE(system) <trace/events/system.h>
+# define UNDEF_TRACE_INCLUDE_PATH
+#else
+# define __TRACE_INCLUDE(system) __stringify(TRACE_INCLUDE_PATH/system.h)
+#endif
+
+# define TRACE_INCLUDE(system) __TRACE_INCLUDE(system)
+
+/* Let the trace headers be reread */
+#define TRACE_HEADER_MULTI_READ
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Make all open coded DECLARE_TRACE nops */
+#undef DECLARE_TRACE
+#define DECLARE_TRACE(name, proto, args)
+#undef DECLARE_TRACE_CONDITION
+#define DECLARE_TRACE_CONDITION(name, proto, args, cond)
+
+#undef DECLARE_TRACE_EVENT
+#define DECLARE_TRACE_EVENT(name, proto, args)
+#undef DECLARE_TRACE_EVENT_CONDITION
+#define DECLARE_TRACE_EVENT_CONDITION(name, proto, args, cond)
+
+#ifdef TRACEPOINTS_ENABLED
+#include <trace/trace_events.h>
+#include <trace/perf.h>
+#include <trace/bpf_probe.h>
+#endif
+
+#undef TRACE_EVENT
+#undef TRACE_EVENT_FN
+#undef TRACE_EVENT_FN_COND
+#undef TRACE_EVENT_SYSCALL
+#undef TRACE_EVENT_CONDITION
+#undef TRACE_EVENT_NOP
+#undef DEFINE_EVENT_NOP
+#undef DECLARE_EVENT_CLASS
+#undef DEFINE_EVENT
+#undef DEFINE_EVENT_FN
+#undef DEFINE_EVENT_PRINT
+#undef DEFINE_EVENT_CONDITION
+#undef TRACE_HEADER_MULTI_READ
+#undef DECLARE_TRACE
+#undef DECLARE_TRACE_CONDITION
+#undef DECLARE_TRACE_EVENT
+#undef DECLARE_TRACE_EVENT_CONDITION
+
+/* Only undef what we defined in this file */
+#ifdef UNDEF_TRACE_INCLUDE_FILE
+# undef TRACE_INCLUDE_FILE
+# undef UNDEF_TRACE_INCLUDE_FILE
+#endif
+
+#ifdef UNDEF_TRACE_INCLUDE_PATH
+# undef TRACE_INCLUDE_PATH
+# undef UNDEF_TRACE_INCLUDE_PATH
+#endif
+
+#ifdef CREATE_RUST_TRACE_POINTS
+# undef DEFINE_RUST_DO_TRACE
+# define DEFINE_RUST_DO_TRACE(name, proto, args)
+#endif
+
+/* We may be processing more files */
+#define CREATE_TRACE_POINTS
+
+#endif /* CREATE_TRACE_POINTS */