[lttng-dev] [PATCH lttng-tools] Fix: systematic overwrite of union values on add context

[Jonathan Rajotte]

Bug introduced in commit 2001793c1141e89b34e70efb28b27ec0cc8e6d47

The type and config fields of the lttng_event_perf_counter_ctx member of
lttng_event_context union would always be set to zero.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
---
 src/lib/lttng-ctl/lttng-ctl.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
index fe0527d..436f358 100644
--- a/src/lib/lttng-ctl/lttng-ctl.c
+++ b/src/lib/lttng-ctl/lttng-ctl.c
@@ -736,9 +736,15 @@ int lttng_add_context(struct lttng_handle *handle,
 		memcpy(buf + provider_len, ctx_name, ctx_len);
 	}
 	memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
-	/* Don't leak application addresses to the sessiond. */
-	lsm.u.context.ctx.u.app_ctx.provider_name = NULL;
-	lsm.u.context.ctx.u.app_ctx.ctx_name = NULL;
+
+	if (ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+		/* Don't leak application addresses to the sessiond.
+		 * This is only necessary when ctx is for an app ctx otherwise
+		 * the value inside the union (type & config) are overwritten.
+		 */
+		lsm.u.context.ctx.u.app_ctx.provider_name = NULL;
+		lsm.u.context.ctx.u.app_ctx.ctx_name = NULL;
+	}
 
 	ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, buf, len, NULL);
 end:
-- 
2.7.0