From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 11 May 2021 14:28:02 +0000 (-0400)
Subject: Fix: java application context segmentation fault
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=239128ca4ff4270a87d03f7098ebb6bf48b6aec7;p=lttng-ust.git

Fix: java application context segmentation fault

Type mismatch for application context private data causes segmentation
faults in the lttng-ust java testsuite.

This can be solved by using the private data provided by the application
context rather than struct lttng_ust_app_ctx, which is not needed
anymore.

This also fixes a memory leak on context add error.

Those issues were introduced by the 2.13 development cycle refactorings.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I19c4e2d0ef6bcb7d4f9c2ffa43a9425661df05c1
---

diff --git a/src/lib/lttng-ust/lttng-context-provider.c b/src/lib/lttng-ust/lttng-context-provider.c
index 8ef552a2..b4118122 100644
--- a/src/lib/lttng-ust/lttng-context-provider.c
+++ b/src/lib/lttng-ust/lttng-context-provider.c
@@ -27,12 +27,6 @@ struct lttng_ust_registered_context_provider {
 	struct cds_hlist_node node;
 };
 
-struct lttng_ust_app_ctx {
-	char *name;
-	struct lttng_ust_event_field *event_field;
-	struct lttng_ust_type_common *type;
-};
-
 #define CONTEXT_PROVIDER_HT_BITS	12
 #define CONTEXT_PROVIDER_HT_SIZE	(1U << CONTEXT_PROVIDER_HT_BITS)
 struct context_provider_ht {
@@ -125,16 +119,6 @@ end:
 	free(reg_provider);
 }
 
-static void destroy_app_ctx(void *priv)
-{
-	struct lttng_ust_app_ctx *app_ctx = (struct lttng_ust_app_ctx *) priv;
-
-	free(app_ctx->name);
-	free(app_ctx->event_field);
-	free(app_ctx->type);
-	free(app_ctx);
-}
-
 /*
  * Called with ust mutex held.
  * Add application context to array of context, even if the application
@@ -150,7 +134,6 @@ int lttng_ust_add_app_context_to_ctx_rcu(const char *name,
 	struct lttng_ust_ctx_field new_field = { 0 };
 	struct lttng_ust_event_field *event_field = NULL;
 	struct lttng_ust_type_common *type = NULL;
-	struct lttng_ust_app_ctx *app_ctx = NULL;
 	char *ctx_name;
 	int ret;
 
@@ -171,11 +154,6 @@ int lttng_ust_add_app_context_to_ctx_rcu(const char *name,
 		ret = -ENOMEM;
 		goto error_field_type_alloc;
 	}
-	app_ctx = zmalloc(sizeof(struct lttng_ust_app_ctx));
-	if (!app_ctx) {
-		ret = -ENOMEM;
-		goto error_app_ctx_alloc;
-	}
 	event_field->name = ctx_name;
 	type->type = lttng_ust_type_dynamic;
 	event_field->type = type;
@@ -189,25 +167,24 @@ int lttng_ust_add_app_context_to_ctx_rcu(const char *name,
 		new_field.get_size = provider->get_size;
 		new_field.record = provider->record;
 		new_field.get_value = provider->get_value;
+		new_field.priv = provider->priv;
 	} else {
 		new_field.get_size = lttng_ust_dummy_get_size;
 		new_field.record = lttng_ust_dummy_record;
 		new_field.get_value = lttng_ust_dummy_get_value;
+		new_field.priv = NULL;
 	}
-	new_field.destroy = destroy_app_ctx;
-	new_field.priv = app_ctx;
 	/*
 	 * For application context, add it by expanding
 	 * ctx array.
 	 */
 	ret = lttng_ust_context_append_rcu(ctx, &new_field);
 	if (ret) {
-		destroy_app_ctx(app_ctx);
-		return ret;
+		goto error_append;
 	}
 	return 0;
 
-error_app_ctx_alloc:
+error_append:
 	free(type);
 error_field_type_alloc:
 	free(ctx_name);