SDL leaks memory, as reported by valgrind

Game Development
1

Even the simplest SDL program leaks memory, as reported by valgrind.

This is the program:

#include "SDL.h"
int main(int argc, char* args[])
{
    SDL_Init(SDL_INIT_VIDEO);
    SDL_Quit();
    return 0;
}

This is the output of valgrind:

==1161== Memcheck, a memory error detector
==1161== Copyright (C) 2002-2015, and GNU GPL’d, by Julian Seward et al.
==1161== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==1161== Command: ./(…omitted…)
==1161==
–1161-- WARNING: Serious error when reading debug info
–1161-- When reading debug info from /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0:
–1161-- Ignoring non-Dwarf2/3/4 block in .debug_info
–1161-- WARNING: Serious error when reading debug info
–1161-- When reading debug info from /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0:
–1161-- Last block truncated in .debug_info; ignoring
–1161-- WARNING: Serious error when reading debug info
–1161-- When reading debug info from /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0:
–1161-- parse_CU_Header: is neither DWARF2 nor DWARF3 nor DWARF4
==1161== Syscall param writev(vector[…]) points to uninitialised byte(s)
==1161== at 0x579EFE0: __writev_nocancel (syscall-template.S:84)
==1161== by 0x8C86F28: ??? (in /usr/lib/x86_64-linux-gnu/libxcb.so.1.1.0)
==1161== by 0x8C8731C: ??? (in /usr/lib/x86_64-linux-gnu/libxcb.so.1.1.0)
==1161== by 0x8C873A4: xcb_writev (in /usr/lib/x86_64-linux-gnu/libxcb.so.1.1.0)
==1161== by 0x5F3C54D: _XSend (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==1161== by 0x5F3CA41: _XReply (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==1161== by 0x5F2760E: XInternAtom (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==1161== by 0x544EAEA: SetWindowBordered (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0)
==1161== by 0x544F8F1: X11_CreateWindow (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0)
==1161== by 0x5441148: SDL_CreateWindow_REAL (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0)
==1161== by 0x5440F34: SDL_VideoInit_REAL (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0)
==1161== by 0x53A8396: SDL_InitSubSystem_REAL (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0)
==1161== Address 0xc18ddb3 is 35 bytes inside a block of size 16,384 alloc’d
==1161== at 0x4C2FB55: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1161== by 0x5F2C722: XOpenDisplay (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==1161== by 0x5074E69: ??? (in /usr/NX/scripts/vgl/librrfaker.so)
==1161== by 0x50768D1: XOpenDisplay (in /usr/NX/scripts/vgl/librrfaker.so)
==1161== by 0x544DDB4: X11_CreateDevice (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0)
==1161== by 0x5440EE0: SDL_VideoInit_REAL (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0)
==1161== by 0x53A8396: SDL_InitSubSystem_REAL (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.4.0)
==1161== by 0x40060D: main (in (…omitted…))
==1161==
==1161==
==1161== HEAP SUMMARY:
==1161== in use at exit: 112,141 bytes in 474 blocks
==1161== total heap usage: 10,970 allocs, 10,496 frees, 672,833,828 bytes allocated
==1161==
==1161== LEAK SUMMARY:
==1161== definitely lost: 17,920 bytes in 3 blocks
==1161== indirectly lost: 0 bytes in 0 blocks
==1161== possibly lost: 0 bytes in 0 blocks
==1161== still reachable: 94,221 bytes in 471 blocks
==1161== suppressed: 0 bytes in 0 blocks
==1161== Rerun with --leak-check=full to see details of leaked memory
==1161==
==1161== For counts of detected and suppressed errors, rerun with: -v
==1161== Use --track-origins=yes to see where uninitialised values come from
==1161== ERROR SUMMARY: 2 errors from 1 contexts (suppressed: 1 from 1)

So my question is: Does SDL have to leak memory? Is there any workaround to stop the leakage? Thanks.

Environment:

  • Ubuntu 16.04 64 bit.
  • SDL 2.0
  • g++ 5.4.0
  • Valgrind 3.11.0

A follow-up: this is the valgrind report of leakage on another Linux:

Untitled1
Untitled1773×278 44.4 KB

Environment:

  • Ubuntu 18.04 64 bit.
  • SDL 2.0
  • g++ 7.3.0
  • Valgrind 3.13.0
2

This is a known issue with X11 and some other libraries on Linux. They do not actually leak but are detected as leaks.

1 Like
3

Hi, still open.
using mint21.2 with cinnamon i get a leak message with “widelands”

>     [03:52:10.490 real] INFO: SoundHandler: Closing 1 time, 22050 Hz,
>     format
>     32784, 2 channels
>     [03:52:10.490 real] INFO: SoundHandler: SDL_AUDIODRIVER pulseaudio
>
>     =================================================================
>     ==11630==ERROR: LeakSanitizer: detected memory leaks
>
>     Direct leak of 160 byte(s) in 1 object(s) allocated from:
>           #0 0x7f0e78e35a57 in __interceptor_calloc
>     ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
>           #1 0x7f0e76d4dd3f
>     (/lib/x86_64-linux-gnu/libSDL2-2.0.so.0+0xf7d3f)
>
>     SUMMARY: AddressSanitizer: 160 byte(s) leaked in 1 allocation(s).
>
>

After email
On 8/7/24 21:22, Sam Lantinga wrote:

Can you build SDL with debug symbols and get a stack trace of where this
allocation occurred?

i now would like to build it
but this thread says PERHAPS its a faulty message ???
and
what will i need to build the debug symbols
OR/AND how to check if its already done?
cheers

i am native z80;-)

4

Sorry, to not answer your questions about building SDL with debug flags, but I want to draw your attention to this and I hope it works for your project:

There was a recent issue that Chvolow24 reported and solved here on a Mac system where the Address Sanitizer was actually the culprit in causing a leak linked to it’s trying to track memory being passed between the audio driver and SDL audio device.
I see you are on Linux, but your output mentions the Address Sanitizer and Audio Drivers. Perhaps the Sanitizer is still a problem here.

What happens if you remove Address Sanitizer from your compiler arguments and use Valgrind instead?

Edit:
To (hopefully) answer your actual question, you can build a debug version using this cmake argument:
cmake ~/SDL -DCMAKE_BUILD_TYPE=Debug

5

HI, thanks for your reply, the sanitiser report is made by widelands widelands.org
its a big auto install once the dev are complete and i have no clue if Address Sanitizer and Valgrind are equal in use
for an SDL install i probably have to download it first and check a lot off dev, i use synaptic for regular installs but i do install eg z88dk

edit:
found on widelands org the install line
$ ./compile.sh -r for a release build, or $ ./compile.sh -a for a debug build without AddressSanitizer
i better do that first.