[PATCH v5 4/4] tracing: Add might_fault() check in __DECLARE_TRACE_SYSCALL

[Mathieu Desnoyers]

Catch incorrect use of syscall tracepoints even if no probes are
registered by adding a might_fault() check in trace_##name()
emitted by __DECLARE_TRACE_SYSCALL.

Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Jordan Rife <jrife@xxxxxxxxxx>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Michael Jeanson <mjeanson@xxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Yonghong Song <yhs@xxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
Cc: bpf@xxxxxxxxxxxxxxx
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Jordan Rife <jrife@xxxxxxxxxx>
---
Changes since v4:
- Move might_fault() to trace_##name() emitted by __DECLARE_TRACE_SYSCALL
  so it is validated even when the tracepoint is disabled.
---
 include/linux/tracepoint.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 906f3091d23d..425123e921ac 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -301,6 +301,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), cond, PARAMS(data_proto)) \
 	static inline void trace_##name(proto)				\
 	{								\
+		might_fault();						\
 		if (static_branch_unlikely(&__tracepoint_##name.key))	\
 			__DO_TRACE(name,				\
 				TP_ARGS(args),				\
-- 
2.39.5