Fix: lttng-add-context: leak of application context parameters

Issue observed
--------------

ASAN reports the following leak when running the
tests/regression/tools/context/test_ust.py test suite:

  Direct leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x7f32e5ae0cd1 in __interceptor_calloc /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:77
    #1 0x5653e1092088 in zmalloc_internal ../../../src/common/macros.hpp:60
    #2 0x5653e10922b3 in char* calloc<char>(unsigned long) string-utils/../macros.hpp:113
    #3 0x5653e119d68f in get_context_type commands/add_context.cpp:1012
    #4 0x5653e119ddf5 in cmd_add_context(int, char const**) commands/add_context.cpp:1059
    #5 0x5653e11e12e7 in handle_command /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:237
    #6 0x5653e11e2027 in parse_args /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:427
    #7 0x5653e11e24e1 in _main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:474
    #8 0x5653e11e25bd in main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:485
    lttng#9 0x7f32e3e3984f  (/usr/lib/libc.so.6+0x2384f) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e)

  Direct leak of 5 byte(s) in 1 object(s) allocated from:
    #0 0x7f32e5ae0cd1 in __interceptor_calloc /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:77
    #1 0x5653e1092088 in zmalloc_internal ../../../src/common/macros.hpp:60
    #2 0x5653e10922b3 in char* calloc<char>(unsigned long) string-utils/../macros.hpp:113
    #3 0x5653e119d2ae in get_context_type commands/add_context.cpp:1003
    #4 0x5653e119ddf5 in cmd_add_context(int, char const**) commands/add_context.cpp:1059
    #5 0x5653e11e12e7 in handle_command /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:237
    #6 0x5653e11e2027 in parse_args /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:427
    #7 0x5653e11e24e1 in _main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:474
    #8 0x5653e11e25bd in main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:485
    lttng#9 0x7f32e3e3984f  (/usr/lib/libc.so.6+0x2384f) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e)

Cause
-----

The context and provider names are dynamically allocated by
get_context_type() and stored in ctx_type. However, destroy_ctx_type()
never frees those members when the structure is of type
CONTEXT_APP_CONTEXT.

Solution
--------

Free both names when an application context type is destroyed.

Signed-off-by: Jérémie Galarneau <[email protected]>
Change-Id: I86dde1eed9f0cc63499c936cf373b094168035e2

Author: jgalar

src/bin/lttng/commands/add_context.cpp

@@ -812,9 +812,16 @@ static void destroy_ctx_type(struct ctx_type *type)
 	if (!type) {
 		return;
 	}
+
 	if (type->opt) {
 		free(type->opt->symbol);
 	}
+
+	if (type->opt->ctx_type == CONTEXT_APP_CONTEXT) {
+		free(type->opt->u.app_ctx.ctx_name);
+		free(type->opt->u.app_ctx.provider_name);
+	}
+
 	delete type->opt;
 	free(type);
 }