Valgrind tool in linux

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Using valgrind to find memory leaks and invalid memory use

Marslanali/valgrind-linux

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README.md

Using valgrind to find memory leaks and invalid memory use.

There are two ways you can install Valgrind on linux.

Install pre-built valgrind stable release

Download stable release valgrind 3.16.0.

https://www.valgrind.org/downloads/current.html 

Decompress and untar valgrind 3.16.0 using bzip2.

bzip2 -d valgrind-3.16.0.tar.bz2 tar -xf valgrind-3.16.0.tar 

Configure, compile, and install it.

cd valgrind-3.16.0 ./configure make sudo make install 

By default this will install valgrind binaries in /usr/local/bin and libs in /usr/local/lib.

To check version and test whether valgrind installed correctly.

compile valgrind from source, compile and install

git clone git://sourceware.org/git/valgrind.git 

Extract the source code. To follow the instructions in the README file that the clone should give you.

Configure, Compile, and install it.

cd valgrind ./autogen.sh ./configure --prefix=. make sudo make instal 

Example C Program with valgrind

For demonstration, consider following C code.

Compile your C program with -g option. This allows the compiler to collect the debugging information.

cd valgrind-memory-debugging-tool-linux gcc -g -o example1 example1.c ./example1 

Finding memory leaks with valgrind.

valgrind --tool=memcheck --leak-check=yes ./example1 

This will result in following information about the program.

==11587== Memcheck, a memory error detector ==11587== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==11587== Using Valgrind-3.16.0 and LibVEX; rerun with -h for copyright info ==11587== Command: ./example1 ==11587== ==11587== ==11587== HEAP SUMMARY: ==11587== in use at exit: 100 bytes in 1 blocks ==11587== total heap usage: 1 allocs, 0 frees, 100 bytes allocated ==11587== ==11587== 100 bytes in 1 blocks are definitely lost in loss record 1 of 1 ==11587== at 0x4C2DF66: malloc (vg_replace_malloc.c:307) ==11587== by 0x400537: main (example1.c:4) ==11587== ==11587== LEAK SUMMARY: ==11587== definitely lost: 100 bytes in 1 blocks ==11587== indirectly lost: 0 bytes in 0 blocks ==11587== possibly lost: 0 bytes in 0 blocks ==11587== still reachable: 0 bytes in 0 blocks ==11587== suppressed: 0 bytes in 0 blocks ==11587== ==11587== For lists of detected and suppressed errors, rerun with: -s ==11587== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0) 

Finding invalid pointer use with valgrind

Valgrind can also find the use of invalid heap memory using the memcheck tool. For instance, if you allocate an array with malloc or new and then try to access a location past the end of the array.

Valgrind will detect it. For instance, running the following program, example2, through valgrind

Compile your C program with -g option. This allows the compiler to collect the debugging information.

cd valgrind-memory-debugging-tool-linux gcc -g -o example2 example2.c ./example2 

Finding memory leaks with valgrind.

valgrind --tool=memcheck --leak-check=yes ./example2 

This will result in following information about the program.

==11673== Memcheck, a memory error detector ==11673== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==11673== Using Valgrind-3.16.0 and LibVEX; rerun with -h for copyright info ==11673== Command: ./example2 ==11673== ==11673== Invalid write of size 1 ==11673== at 0x400544: main (example2.c:6) ==11673== Address 0x520504a is 0 bytes after a block of size 10 alloc'd ==11673== at 0x4C2DF66: malloc (vg_replace_malloc.c:307) ==11673== by 0x400537: main (example2.c:5) ==11673== ==11673== ==11673== HEAP SUMMARY: ==11673== in use at exit: 10 bytes in 1 blocks ==11673== total heap usage: 1 allocs, 0 frees, 10 bytes allocated ==11673== ==11673== 10 bytes in 1 blocks are definitely lost in loss record 1 of 1 ==11673== at 0x4C2DF66: malloc (vg_replace_malloc.c:307) ==11673== by 0x400537: main (example2.c:5) ==11673== ==11673== LEAK SUMMARY: ==11673== definitely lost: 10 bytes in 1 blocks ==11673== indirectly lost: 0 bytes in 0 blocks ==11673== possibly lost: 0 bytes in 0 blocks ==11673== still reachable: 0 bytes in 0 blocks ==11673== suppressed: 0 bytes in 0 blocks ==11673== ==11673== For lists of detected and suppressed errors, rerun with: -s ==11673== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0) 

About

Using valgrind to find memory leaks and invalid memory use

Источник

Ubuntu Wiki

Valgrind is a suite of tools for debugging and profiling programs. There are three tools: a memory error detector, a time profiler, and a space profiler.

For debugging purposes, the memory error detector is a handy tool.

Memory error detection

The most important of these is the memory error detector, which tracks the usage of every single bit in a program, and warns if there’s something suspicious. Valgrind can detect if memory is used before it has a value, memory is leaked, or memory is used twice.

This makes it ideal for tracking down segmentation faults, bus errors, and general memory leaks.

Please ensure you have packages with debug symbols installed. You can do this by following the instructions at DebuggingProgramCrash.

Make sure Valgrind is installed.

sudo apt-get install valgrind

G_SLICE=always-malloc G_DEBUG=gc-friendly valgrind -v —tool=memcheck —leak-check=full —num-callers=40 —log-file=valgrind.log $(which )

1. N.B. valgrind can’t solve paths, so you should feed it the full program path, to get it: $(which )
2. The program will start. It may take a while; this is normal, because Valgrind must perform extensive checking to detect memory errors.
3. Perform any actions necessary to reproduce the crash.
4. Package up the log files (no need if there is only one):

tar -zcf valgrind-logs-.tar.gz valgrind.log*

Источник

Debugging C++ code with Valgrind on Linux

A brief intro about how to debug and optimize C++ development in linux using Valgrind.

Finding memory bugs like memory-leaks, memory corruptions and memory access violations can be difficult if you don’t have the right tool to help you narrow down the scope and provide clues. This is what Valgrind does good for code written in C/C++, it can save you hours of frustration.

How to run

You can install valgrind using your package manager (for Ubuntu sudo apt install valgrind ). Your program can be complied with any compiler, but try to keep it on no optimizations to get most of valgrind)

For your program named hello , run

Understanding Valgrind

Valgrind is a debugging tool which is available on Linux, it’s an opensource project and is free to use. Valgrind helps with memory leak detection, threading bugs and can help optimize code using its profiling support. Valgrind is designed to work non-intrusively as possible with existing executable, this means you don’t need to re-link or re-build a binary in order to use Valgrind features. Simply run Valgrind passing it operational parameters and the executable to be tested along with any parameters the executable might accept.

The executable is run on a synthetic CPU provided by the Valgrind core, every single instruction executed is simulated, which will cause the executable to run much slower. Lets look at Valgrind by testing the Linux date command from the shell.

==20943== Memcheck, a memory error detector ==20943== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al. ==20943== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info ==20943== Command: ./hello ==20943==  ================================================================================================== Hello World! ================================================================================================== ==20943==  ==20943== HEAP SUMMARY: ==20943==  in use at exit: 72,768 bytes in 3 blocks ==20943==  total heap usage: 6,247 allocs, 6,244 frees, 1,071,757 bytes allocated ==20943==  ==20943== 32 bytes in 1 blocks are still reachable in loss record 1 of 3 ==20943== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==20943== by 0x6340E77: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0) ==20943== by 0x63F841E: sk_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0) ==20943== by 0x60B94F9: .  (in /lib/x86_64-linux-gnu/libssl.so.1.0.0) ==20943== by 0x60BB5F8: SSL_COMP_get_compression_methods (in /lib/x86_64-linux-gnu/libssl.so.1.0.0) ==20943== by 0x60C0D82: SSL_library_init (in /lib/x86_64-linux-gnu/libssl.so.1.0.0) ==20943== by 0x52BA77: boost::asio::ssl::detail::openssl_init_base::do_init::do_init() (openssl_init.ipp:39) ==20943== by 0x52BE42: boost::asio::ssl::detail::openssl_init_base::instance() (openssl_init.ipp:131) ==20943== by 0x52C955: boost::asio::ssl::detail::openssl_init::openssl_init() (openssl_init.hpp:60) ==20943== by 0x562DB2B: __static_initialization_and_destruction_0(int, int) (openssl_init.hpp:90) ==20943== by 0x562E538: _GLOBAL__sub_I_http_client.cpp (http_client.cpp:426) ==20943== by 0x40106C9: call_init.part.0 (dl-init.c:72) ==20943==  ==20943== 32 bytes in 1 blocks are still reachable in loss record 2 of 3 ==20943== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==20943== by 0x6340E77: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0) ==20943== by 0x63F843C: sk_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0) ==20943== by 0x60B94F9: .  (in /lib/x86_64-linux-gnu/libssl.so.1.0.0) ==20943== by 0x60BB5F8: SSL_COMP_get_compression_methods (in /lib/x86_64-linux-gnu/libssl.so.1.0.0) ==20943== by 0x60C0D82: SSL_library_init (in /lib/x86_64-linux-gnu/libssl.so.1.0.0) ==20943== by 0x52BA77: boost::asio::ssl::detail::openssl_init_base::do_init::do_init() (openssl_init.ipp:39) ==20943== by 0x52BE42: boost::asio::ssl::detail::openssl_init_base::instance() (openssl_init.ipp:131) ==20943== by 0x52C955: boost::asio::ssl::detail::openssl_init::openssl_init() (openssl_init.hpp:60) ==20943== by 0x562DB2B: __static_initialization_and_destruction_0(int, int) (openssl_init.hpp:90) ==20943== by 0x562E538: _GLOBAL__sub_I_http_client.cpp (http_client.cpp:426) ==20943== by 0x40106C9: call_init.part.0 (dl-init.c:72) ==20943==  ==20943== 72,704 bytes in 1 blocks are still reachable in loss record 3 of 3 ==20943== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==20943== by 0x67ACEFF: .  (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21) ==20943== by 0x40106C9: call_init.part.0 (dl-init.c:72) ==20943== by 0x40107DA: call_init (dl-init.c:30) ==20943== by 0x40107DA: _dl_init (dl-init.c:120) ==20943== by 0x4000C69: .  (in /lib/x86_64-linux-gnu/ld-2.23.so) ==20943==  ==20943== LEAK SUMMARY: ==20943==  definitely lost: 0 bytes in 0 blocks ==20943==  indirectly lost: 0 bytes in 0 blocks ==20943==  possibly lost: 0 bytes in 0 blocks ==20943==  still reachable: 72,768 bytes in 3 blocks ==20943==  suppressed: 0 bytes in 0 blocks ==20943==  ==20943== For counts of detected and suppressed errors, rerun with: -v ==20943== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Источник