X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=probes%2Flttng-events.h;h=d486994f3a0c2202741037c8ef68ffe5ebd16bc5;hb=edb5c2da83545004c5f556accb79d010a6b1e3a9;hp=54a451e53388eda82d279d3ec1a98e6a398314f0;hpb=d0255731fe93baede90f26d19aa4388403973554;p=lttng-modules.git

diff --git a/probes/lttng-events.h b/probes/lttng-events.h
index 54a451e5..d486994f 100644
--- a/probes/lttng-events.h
+++ b/probes/lttng-events.h
@@ -341,11 +341,13 @@ static __used struct lttng_probe_desc TP_ID(__probe_desc___, TRACE_SYSTEM) = {
 	__event_len += __dynamic_len[__dynamic_len_idx++] = strlen(_src) + 1;
 
 /*
- * strlen_user includes \0. If returns 0, it faulted.
+ * strlen_user includes \0. If returns 0, it faulted, so we set size to
+ * 1 (\0 only).
  */
 #undef __string_from_user
 #define __string_from_user(_item, _src)					       \
-	__event_len += __dynamic_len[__dynamic_len_idx++] = strlen_user(_src);
+	__event_len += __dynamic_len[__dynamic_len_idx++] =		       \
+		max_t(size_t, strlen_user(_src), 1);
 
 #undef TP_PROTO
 #define TP_PROTO(args...) args
@@ -543,9 +545,7 @@ __assign_##dest##_2:							\
 	goto __end_field_##dest;
 
 /*
- * If string length is zero, this means reading the string faulted, so
- * we simply put a \0. If string length is larger than 0, it is the
- * string length including the final \0.
+ * The string length including the final \0.
  */
 #undef tp_copy_string_from_user
 #define tp_copy_string_from_user(dest, src)				\
@@ -557,7 +557,7 @@ __assign_##dest##_2:							\
 			(void) __typemap.dest;				\
 		lib_ring_buffer_align_ctx(&__ctx, ltt_alignof(__typemap.dest));\
 		__ustrlen = __get_dynamic_array_len(dest);		\
-		if (likely(__ustrlen) > 1) {				\
+		if (likely(__ustrlen > 1)) {				\
 			__chan->ops->event_write_from_user(&__ctx, src,	\
 				__ustrlen - 1);				\
 		}							\