Fix: ctf_string() should handle NULL pointers

The regmap instrumentation can send a NULL string (e.g. on ARM32).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/probes/lttng-tracepoint-event-impl.h b/probes/lttng-tracepoint-event-impl.h
index ba906ac49c01fa46b34bf8e8d4a87570ab3b3a9e..45c38ff43b21cc6dab85b7ff72a8fe3996564725 100644 (file)
--- a/probes/lttng-tracepoint-event-impl.h
+++ b/probes/lttng-tracepoint-event-impl.h
@@ -35,6 +35,8 @@
 #include <lttng-events.h>
 #include <lttng-tracer-core.h>
 
+#define __LTTNG_NULL_STRING    "(null)"
+
 /*
  * Macro declarations used for all stages.
  */
@@ -392,7 +394,7 @@ static void __event_probe__##_name(void *__data);
                        max_t(size_t, lttng_strlen_user_inatomic(_src), 1);    \
        else                                                                   \
                __event_len += __dynamic_len[__dynamic_len_idx++] =            \
-                       strlen(_src) + 1;
+                       strlen((_src) ? (_src) : __LTTNG_NULL_STRING) + 1;
 
 #undef TP_PROTO
 #define TP_PROTO(...)  __VA_ARGS__
@@ -581,7 +583,8 @@ static inline size_t __event_get_size__##_name(size_t *__dynamic_len,             \
 #undef _ctf_string
 #define _ctf_string(_item, _src, _user, _nowrite)                             \
        {                                                                      \
-               const void *__ctf_tmp_ptr = (_src);                            \
+               const void *__ctf_tmp_ptr =                                    \
+                       ((_src) ? (_src) : __LTTNG_NULL_STRING);               \
                memcpy(__stack_data, &__ctf_tmp_ptr, sizeof(void *));          \
                __stack_data += sizeof(void *);                                \
        }
@@ -871,12 +874,16 @@ static inline size_t __event_get_align__##_name(void *__tp_locvar)              \
 
 #undef _ctf_string
 #define _ctf_string(_item, _src, _user, _nowrite)                      \
-       lib_ring_buffer_align_ctx(&__ctx, lttng_alignof(*(_src)));      \
        if (_user) {                                                    \
+               lib_ring_buffer_align_ctx(&__ctx, lttng_alignof(*(_src))); \
                __chan->ops->event_strcpy_from_user(&__ctx, _src,       \
                        __get_dynamic_len(dest));                       \
        } else {                                                        \
-               __chan->ops->event_strcpy(&__ctx, _src,                 \
+               const char *__ctf_tmp_string =                          \
+                       ((_src) ? (_src) : __LTTNG_NULL_STRING);        \
+               lib_ring_buffer_align_ctx(&__ctx,                       \
+                       lttng_alignof(*__ctf_tmp_string));              \
+               __chan->ops->event_strcpy(&__ctx, __ctf_tmp_string,     \
                        __get_dynamic_len(dest));                       \
        }