Fix Memory Leak in Client Initialization

[GeorgeBerdovskiy]

In src/client.rs, the C function rd_kafka_new is called with a pointer to a NativeClientConfig object. According to a comment in the implementation of rd_kafka_new, it takes ownership of the config on success. That means when the function fails, the caller is responsible for freeing it. See line 2445 of src/rdkafka.c in the librdkafka repository.

By calling ManuallyDrop::new(native_config), the Rust client initialization code prevents the compiler from dropping the config automatically. Otherwise, it would be dropped even though rd_kafka_new took ownership of it, resulting in possible UAF bugs.

Because of this, when rd_kafka_new fails, the config isn't dropped, resulting in a memory leak. I confirmed this using a simple Rust program and Valgrind.

Code

use rdkafka::config::ClientConfig;
use rdkafka::client::{DefaultClientContext, Client};

use rdkafka_sys::RDKafkaType;

fn main() {
    println!("Starting memory leak reproduction...");

    let mut binding = ClientConfig::new();
    let config = binding
        .set("acks", "1")
        .set("enable.idempotence", "true");

    let native_config = config.create_native_config().unwrap();

    let err = Client::new(
        &config,
        native_config,
        RDKafkaType::RD_KAFKA_PRODUCER,
        DefaultClientContext,
    );

    if err.is_err() {
        println!("Client creation errored out as expected");
    }
}

Command

valgrind --leak-check=full --show-leak-kinds=all \
  target/debug/memory-leak-repro  --test-threads=1

Output

==16317== Memcheck, a memory error detector
==16317== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==16317== Using Valgrind-3.22.0 and LibVEX; rerun with -h for copyright info
==16317== Command: target/debug/memory-leak-repro --test-threads=1
==16317==
Starting memory leak reproduction...
Client creation errored out as expected
==16317==
==16317== HEAP SUMMARY:
==16317==     in use at exit: 3,386 bytes in 18 blocks
==16317==   total heap usage: 40 allocs, 22 frees, 6,840 bytes allocated
==16317==
==16317== 7 bytes in 1 blocks are indirectly lost in loss record 1 of 7
==16317==    at 0x4885250: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==16317==    by 0x4A4D62F: strdup (strdup.c:42)
==16317==    by 0x161473: rd_strdup (rd.h:158)
==16317==    by 0x161473: rd_kafka_anyconf_set_prop0 (???:1995)
==16317==    by 0x15B297: rd_kafka_anyconf_set (rdkafka_conf.c:2509)
==16317==    by 0x15F0EB: rd_kafka_conf_set (rdkafka_conf.c:2551)
==16317==    by 0x15F0EB: rd_kafka_conf_finalize (???:4154)
==16317==    by 0x137A1F: rd_kafka_new (rdkafka.c:2341)
==16317==    by 0x12B22B: rdkafka::client::Client<C>::new_context_arc (client.rs:261)
==16317==    by 0x12B543: rdkafka::client::Client<C>::new (client.rs:240)
==16317==    by 0x1270B7: memory_leak_repro::main (main.rs:16)
==16317==    by 0x12618B: core::ops::function::FnOnce::call_once (library/core/src/ops/function.rs:250)
==16317==    by 0x1262E7: std::sys::backtrace::__rust_begin_short_backtrace (library/std/src/sys/backtrace.rs:166)
==16317==    by 0x125B53: std::rt::lang_start::{{closure}} (library/std/src/rt.rs:206)
==16317==
==16317== 20 bytes in 2 blocks are indirectly lost in loss record 2 of 7
==16317==    at 0x4885250: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==16317==    by 0x4A4D62F: strdup (strdup.c:42)
==16317==    by 0x161473: rd_strdup (rd.h:158)
==16317==    by 0x161473: rd_kafka_anyconf_set_prop0 (???:1995)
==16317==    by 0x15AFE7: rd_kafka_defaultconf_set (rdkafka_conf.c:2441)
==16317==    by 0x15AFE7: rd_kafka_topic_conf_new (???:2461)
==16317==    by 0x15B10B: rd_kafka_conf_set (rdkafka_conf.c:2563)
==16317==    by 0x129173: rdkafka::config::NativeClientConfig::set (config.rs:174)
==16317==    by 0x128E1B: rdkafka::config::ClientConfig::create_native_config (config.rs:299)
==16317==    by 0x126FF7: memory_leak_repro::main (main.rs:14)
==16317==    by 0x12618B: core::ops::function::FnOnce::call_once (library/core/src/ops/function.rs:250)
==16317==    by 0x1262E7: std::sys::backtrace::__rust_begin_short_backtrace (library/std/src/sys/backtrace.rs:166)
==16317==    by 0x125B53: std::rt::lang_start::{{closure}} (library/std/src/rt.rs:206)
==16317==    by 0x2AAA53: call_once<(), (dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (function.rs:287)
==16317==    by 0x2AAA53: do_call<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<i32, &(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panic.rs:359)
==16317==    by 0x2AAA53: {closure#0} (rt.rs:175)
==16317==    by 0x2AAA53: do_call<std::rt::lang_start_internal::{closure_env#0}, isize> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<isize, std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<std::rt::lang_start_internal::{closure_env#0}, isize> (panic.rs:359)
==16317==    by 0x2AAA53: std::rt::lang_start_internal (rt.rs:171)
==16317==
==16317== 46 bytes in 2 blocks are indirectly lost in loss record 3 of 7
==16317==    at 0x4885250: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==16317==    by 0x16140F: rd_malloc (rd.h:141)
==16317==    by 0x16140F: rd_kafkap_str_new (rdkafka_proto.h:315)
==16317==    by 0x16140F: rd_kafka_anyconf_set_prop0 (???:2006)
==16317==    by 0x15AEC3: rd_kafka_defaultconf_set (rdkafka_conf.c:2441)
==16317==    by 0x15AEC3: rd_kafka_conf_new (???:2452)
==16317==    by 0x128D13: rdkafka::config::ClientConfig::create_native_config (config.rs:297)
==16317==    by 0x126FF7: memory_leak_repro::main (main.rs:14)
==16317==    by 0x12618B: core::ops::function::FnOnce::call_once (library/core/src/ops/function.rs:250)
==16317==    by 0x1262E7: std::sys::backtrace::__rust_begin_short_backtrace (library/std/src/sys/backtrace.rs:166)
==16317==    by 0x125B53: std::rt::lang_start::{{closure}} (library/std/src/rt.rs:206)
==16317==    by 0x2AAA53: call_once<(), (dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (function.rs:287)
==16317==    by 0x2AAA53: do_call<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<i32, &(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panic.rs:359)
==16317==    by 0x2AAA53: {closure#0} (rt.rs:175)
==16317==    by 0x2AAA53: do_call<std::rt::lang_start_internal::{closure_env#0}, isize> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<isize, std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<std::rt::lang_start_internal::{closure_env#0}, isize> (panic.rs:359)
==16317==    by 0x2AAA53: std::rt::lang_start_internal (rt.rs:171)
==16317==    by 0x125B2B: std::rt::lang_start (library/std/src/rt.rs:205)
==16317==    by 0x127187: main (in /home/memory-leak-repro/target/debug/memory-leak-repro)
==16317==
==16317== 217 bytes in 10 blocks are indirectly lost in loss record 4 of 7
==16317==    at 0x4885250: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==16317==    by 0x4A4D62F: strdup (strdup.c:42)
==16317==    by 0x161473: rd_strdup (rd.h:158)
==16317==    by 0x161473: rd_kafka_anyconf_set_prop0 (???:1995)
==16317==    by 0x15AEC3: rd_kafka_defaultconf_set (rdkafka_conf.c:2441)
==16317==    by 0x15AEC3: rd_kafka_conf_new (???:2452)
==16317==    by 0x128D13: rdkafka::config::ClientConfig::create_native_config (config.rs:297)
==16317==    by 0x126FF7: memory_leak_repro::main (main.rs:14)
==16317==    by 0x12618B: core::ops::function::FnOnce::call_once (library/core/src/ops/function.rs:250)
==16317==    by 0x1262E7: std::sys::backtrace::__rust_begin_short_backtrace (library/std/src/sys/backtrace.rs:166)
==16317==    by 0x125B53: std::rt::lang_start::{{closure}} (library/std/src/rt.rs:206)
==16317==    by 0x2AAA53: call_once<(), (dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (function.rs:287)
==16317==    by 0x2AAA53: do_call<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<i32, &(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panic.rs:359)
==16317==    by 0x2AAA53: {closure#0} (rt.rs:175)
==16317==    by 0x2AAA53: do_call<std::rt::lang_start_internal::{closure_env#0}, isize> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<isize, std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<std::rt::lang_start_internal::{closure_env#0}, isize> (panic.rs:359)
==16317==    by 0x2AAA53: std::rt::lang_start_internal (rt.rs:171)
==16317==    by 0x125B2B: std::rt::lang_start (library/std/src/rt.rs:205)
==16317==    by 0x127187: main (in /home/memory-leak-repro/target/debug/memory-leak-repro)
==16317==
==16317== 384 bytes in 1 blocks are indirectly lost in loss record 5 of 7
==16317==    at 0x488C0AC: calloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==16317==    by 0x15AFAB: rd_calloc (rd.h:135)
==16317==    by 0x15AFAB: rd_kafka_topic_conf_new (???:2458)
==16317==    by 0x15B10B: rd_kafka_conf_set (rdkafka_conf.c:2563)
==16317==    by 0x129173: rdkafka::config::NativeClientConfig::set (config.rs:174)
==16317==    by 0x128E1B: rdkafka::config::ClientConfig::create_native_config (config.rs:299)
==16317==    by 0x126FF7: memory_leak_repro::main (main.rs:14)
==16317==    by 0x12618B: core::ops::function::FnOnce::call_once (library/core/src/ops/function.rs:250)
==16317==    by 0x1262E7: std::sys::backtrace::__rust_begin_short_backtrace (library/std/src/sys/backtrace.rs:166)
==16317==    by 0x125B53: std::rt::lang_start::{{closure}} (library/std/src/rt.rs:206)
==16317==    by 0x2AAA53: call_once<(), (dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (function.rs:287)
==16317==    by 0x2AAA53: do_call<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<i32, &(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panic.rs:359)
==16317==    by 0x2AAA53: {closure#0} (rt.rs:175)
==16317==    by 0x2AAA53: do_call<std::rt::lang_start_internal::{closure_env#0}, isize> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<isize, std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<std::rt::lang_start_internal::{closure_env#0}, isize> (panic.rs:359)
==16317==    by 0x2AAA53: std::rt::lang_start_internal (rt.rs:171)
==16317==    by 0x125B2B: std::rt::lang_start (library/std/src/rt.rs:205)
==16317==    by 0x127187: main (in /home/memory-leak-repro/target/debug/memory-leak-repro)
==16317==
==16317== 544 bytes in 1 blocks are still reachable in loss record 6 of 7
==16317==    at 0x4885250: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==16317==    by 0x2ADACB: alloc (alloc.rs:95)
==16317==    by 0x2ADACB: alloc_impl_runtime (alloc.rs:190)
==16317==    by 0x2ADACB: alloc_impl (alloc.rs:312)
==16317==    by 0x2ADACB: allocate (alloc.rs:429)
==16317==    by 0x2ADACB: try_new_uninit_in<alloc::collections::btree::node::LeafNode<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo>, alloc::alloc::Global> (boxed.rs:614)
==16317==    by 0x2ADACB: new_uninit_in<alloc::collections::btree::node::LeafNode<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo>, alloc::alloc::Global> (boxed.rs:581)
==16317==    by 0x2ADACB: new<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (node.rs:87)
==16317==    by 0x2ADACB: new_leaf<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (node.rs:225)
==16317==    by 0x2ADACB: insert_entry<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (entry.rs:403)
==16317==    by 0x2ADACB: insert<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (entry.rs:377)
==16317==    by 0x2ADACB: insert<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (map.rs:1053)
==16317==    by 0x2ADACB: std::sys::pal::unix::stack_overflow::thread_info::set_current_info (thread_info.rs:122)
==16317==    by 0x2AA98F: init (stack_overflow.rs:179)
==16317==    by 0x2AA98F: init (mod.rs:41)
==16317==    by 0x2AA98F: init (rt.rs:118)
==16317==    by 0x2AA98F: {closure#0} (rt.rs:173)
==16317==    by 0x2AA98F: do_call<std::rt::lang_start_internal::{closure_env#0}, isize> (panicking.rs:581)
==16317==    by 0x2AA98F: catch_unwind<isize, std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:544)
==16317==    by 0x2AA98F: catch_unwind<std::rt::lang_start_internal::{closure_env#0}, isize> (panic.rs:359)
==16317==    by 0x2AA98F: std::rt::lang_start_internal (rt.rs:171)
==16317==    by 0x125B2B: std::rt::lang_start (library/std/src/rt.rs:205)
==16317==    by 0x127187: main (in /home/memory-leak-repro/target/debug/memory-leak-repro)
==16317==
==16317== 2,842 (2,168 direct, 674 indirect) bytes in 1 blocks are definitely lost in loss record 7 of 7
==16317==    at 0x488C0AC: calloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==16317==    by 0x15AE87: rd_calloc (rd.h:135)
==16317==    by 0x15AE87: rd_kafka_conf_new (???:2449)
==16317==    by 0x128D13: rdkafka::config::ClientConfig::create_native_config (config.rs:297)
==16317==    by 0x126FF7: memory_leak_repro::main (main.rs:14)
==16317==    by 0x12618B: core::ops::function::FnOnce::call_once (library/core/src/ops/function.rs:250)
==16317==    by 0x1262E7: std::sys::backtrace::__rust_begin_short_backtrace (library/std/src/sys/backtrace.rs:166)
==16317==    by 0x125B53: std::rt::lang_start::{{closure}} (library/std/src/rt.rs:206)
==16317==    by 0x2AAA53: call_once<(), (dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (function.rs:287)
==16317==    by 0x2AAA53: do_call<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<i32, &(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe)> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<&(dyn core::ops::function::Fn<(), Output=i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe), i32> (panic.rs:359)
==16317==    by 0x2AAA53: {closure#0} (rt.rs:175)
==16317==    by 0x2AAA53: do_call<std::rt::lang_start_internal::{closure_env#0}, isize> (panicking.rs:581)
==16317==    by 0x2AAA53: catch_unwind<isize, std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:544)
==16317==    by 0x2AAA53: catch_unwind<std::rt::lang_start_internal::{closure_env#0}, isize> (panic.rs:359)
==16317==    by 0x2AAA53: std::rt::lang_start_internal (rt.rs:171)
==16317==    by 0x125B2B: std::rt::lang_start (library/std/src/rt.rs:205)
==16317==    by 0x127187: main (in /home/memory-leak-repro/target/debug/memory-leak-repro)
==16317==
==16317== LEAK SUMMARY:
==16317==    definitely lost: 2,168 bytes in 1 blocks
==16317==    indirectly lost: 674 bytes in 16 blocks
==16317==      possibly lost: 0 bytes in 0 blocks
==16317==    still reachable: 544 bytes in 1 blocks
==16317==         suppressed: 0 bytes in 0 blocks
==16317==
==16317== For lists of detected and suppressed errors, rerun with: -s
==16317== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

The fix is simple. If rd_kafka_new fails (returns a null pointer), let Rust drop the config automatically. If it succeeds (does NOT return a null pointer), forget the config.

Here's what Valgrind has to say for the same program using my fix.

==29721== Memcheck, a memory error detector
==29721== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==29721== Using Valgrind-3.22.0 and LibVEX; rerun with -h for copyright info
==29721== Command: target/debug/memory-leak-repro --test-threads=1
==29721==
==29721==
==29721== HEAP SUMMARY:
==29721==     in use at exit: 544 bytes in 1 blocks
==29721==   total heap usage: 30,010 allocs, 30,009 frees, 3,199,644 bytes allocated
==29721==
==29721== 544 bytes in 1 blocks are still reachable in loss record 1 of 1
==29721==    at 0x4885250: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==29721==    by 0x2AE423: alloc (alloc.rs:95)
==29721==    by 0x2AE423: alloc_impl_runtime (alloc.rs:190)
==29721==    by 0x2AE423: alloc_impl (alloc.rs:312)
==29721==    by 0x2AE423: allocate (alloc.rs:429)
==29721==    by 0x2AE423: try_new_uninit_in<alloc::collections::btree::node::LeafNode<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo>, alloc::alloc::Global> (boxed.rs:614)
==29721==    by 0x2AE423: new_uninit_in<alloc::collections::btree::node::LeafNode<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo>, alloc::alloc::Global> (boxed.rs:581)
==29721==    by 0x2AE423: new<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (node.rs:87)
==29721==    by 0x2AE423: new_leaf<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (node.rs:225)
==29721==    by 0x2AE423: insert_entry<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (entry.rs:403)
==29721==    by 0x2AE423: insert<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (entry.rs:377)
==29721==    by 0x2AE423: insert<usize, std::sys::pal::unix::stack_overflow::thread_info::ThreadInfo, alloc::alloc::Global> (map.rs:1053)
==29721==    by 0x2AE423: std::sys::pal::unix::stack_overflow::thread_info::set_current_info (thread_info.rs:122)
==29721==    by 0x2AB2E7: init (stack_overflow.rs:179)
==29721==    by 0x2AB2E7: init (mod.rs:41)
==29721==    by 0x2AB2E7: init (rt.rs:118)
==29721==    by 0x2AB2E7: {closure#0} (rt.rs:173)
==29721==    by 0x2AB2E7: do_call<std::rt::lang_start_internal::{closure_env#0}, isize> (panicking.rs:581)
==29721==    by 0x2AB2E7: catch_unwind<isize, std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:544)
==29721==    by 0x2AB2E7: catch_unwind<std::rt::lang_start_internal::{closure_env#0}, isize> (panic.rs:359)
==29721==    by 0x2AB2E7: std::rt::lang_start_internal (rt.rs:171)
==29721==    by 0x12632B: std::rt::lang_start (library/std/src/rt.rs:205)
==29721==    by 0x1261AB: main (in /home/memory-leak-repro/target/debug/memory-leak-repro)
==29721==
==29721== LEAK SUMMARY:
==29721==    definitely lost: 0 bytes in 0 blocks
==29721==    indirectly lost: 0 bytes in 0 blocks
==29721==      possibly lost: 0 bytes in 0 blocks
==29721==    still reachable: 544 bytes in 1 blocks
==29721==         suppressed: 0 bytes in 0 blocks
==29721==
==29721== For lists of detected and suppressed errors, rerun with: -s
==29721== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)