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Bug 2925

Summary: X11-Related Memory Leak
Product: SDL Reporter: Eyal Kalderon <ebkalderon>
Component: videoAssignee: Sam Lantinga <slouken>
Status: RESOLVED INVALID QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 CC: icculus
Version: 2.0.3   
Hardware: x86_64   
OS: Linux   

Description Eyal Kalderon 2015-03-27 06:59:58 UTC 
I compiled the following example OpenGL application from the GL Wiki using GCC: https://www.opengl.org/wiki/Tutorial1:_Creating_a_Cross_Platform_OpenGL_3.2_Context_in_SDL_%28C_/_SDL%29

When running the application within Valgrind, I receive quite a few errors from libX11.

==8482== Memcheck, a memory error detector
==8482== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==8482== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==8482== Command: ./a.out
==8482== 
==8482== Syscall param writev(vector[...]) points to uninitialised byte(s)
==8482==    at 0x5D9BBC0: __writev_nocancel (in /usr/lib/libc-2.21.so)
==8482==    by 0x9AC1CCA: ??? (in /usr/lib/libxcb.so.1.1.0)
==8482==    by 0x9AC20C0: ??? (in /usr/lib/libxcb.so.1.1.0)
==8482==    by 0x9AC2144: xcb_writev (in /usr/lib/libxcb.so.1.1.0)
==8482==    by 0x8F7C18D: _XSend (in /usr/lib/libX11.so.6.3.0)
==8482==    by 0x8F7C681: _XReply (in /usr/lib/libX11.so.6.3.0)
==8482==    by 0x8F67406: XInternAtom (in /usr/lib/libX11.so.6.3.0)
==8482==    by 0x5245E9B: ??? (in /usr/lib/libSDL2-2.0.so.0.2.1)
==8482==    by 0x5246C8A: ??? (in /usr/lib/libSDL2-2.0.so.0.2.1)
==8482==    by 0x523955F: ??? (in /usr/lib/libSDL2-2.0.so.0.2.1)
==8482==    by 0x523936F: ??? (in /usr/lib/libSDL2-2.0.so.0.2.1)
==8482==    by 0x51A15FE: ??? (in /usr/lib/libSDL2-2.0.so.0.2.1)
==8482==  Address 0xa8cda73 is 35 bytes inside a block of size 16,384 alloc'd
==8482==    at 0x4C2C080: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==8482==    by 0x8F6C4E1: XOpenDisplay (in /usr/lib/libX11.so.6.3.0)
==8482==    by 0x5244CB4: ??? (in /usr/lib/libSDL2-2.0.so.0.2.1)
==8482==    by 0x5239330: ??? (in /usr/lib/libSDL2-2.0.so.0.2.1)
==8482==    by 0x51A15FE: ??? (in /usr/lib/libSDL2-2.0.so.0.2.1)
==8482==    by 0x400BFD: main (in /home/ekaljuk/tmp/a.out)
==8482== 
==8482== Conditional jump or move depends on uninitialised value(s)
==8482==    at 0x79A9AF4: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x794B0CD: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x794DAFD: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A85F3A: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A899F7: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x79849BE: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7984D21: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A86641: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A94ECD: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x767DE45: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A9B2CB: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x75E99C0: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482== 
==8482== Syscall param write(buf) points to uninitialised byte(s)
==8482==    at 0x5D96550: __write_nocancel (in /usr/lib/libc-2.21.so)
==8482==    by 0x5D2DC3E: _IO_file_write@@GLIBC_2.2.5 (in /usr/lib/libc-2.21.so)
==8482==    by 0x5D2D2D2: new_do_write (in /usr/lib/libc-2.21.so)
==8482==    by 0x5D2EAC8: _IO_do_write@@GLIBC_2.2.5 (in /usr/lib/libc-2.21.so)
==8482==    by 0x5D2D1CF: _IO_file_sync@@GLIBC_2.2.5 (in /usr/lib/libc-2.21.so)
==8482==    by 0x5D23405: fflush (in /usr/lib/libc-2.21.so)
==8482==    by 0x7957EBB: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7959776: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7956E5B: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x794B180: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x794DAFD: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A85F3A: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==  Address 0x4053018 is not stack'd, malloc'd or (recently) free'd
==8482== 
==8482== Conditional jump or move depends on uninitialised value(s)
==8482==    at 0x79A9AF4: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x794B0CD: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x794D85F: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7AA878B: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7AA9FBC: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x79849BE: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7984D21: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7AA8FE0: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A95ED5: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x767DF52: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A9B2CB: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x75E99C0: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482== 
==8482== Conditional jump or move depends on uninitialised value(s)
==8482==    at 0x79A9AF4: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x794B0CD: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x794BADC: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7AD2DA1: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7AD45D3: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x79849BE: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7984D21: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7AD30F5: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x7A9B353: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x75E99C0: ??? (in /usr/lib/libnvidia-glcore.so.346.47)
==8482==    by 0x400CD9: main (in /home/ekaljuk/tmp/a.out)
==8482== 
==8482== 
==8482== HEAP SUMMARY:
==8482==     in use at exit: 33,315 bytes in 435 blocks
==8482==   total heap usage: 14,841 allocs, 14,406 frees, 105,846,582 bytes allocated
==8482== 
==8482== LEAK SUMMARY:
==8482==    definitely lost: 184 bytes in 5 blocks
==8482==    indirectly lost: 0 bytes in 0 blocks
==8482==      possibly lost: 0 bytes in 0 blocks
==8482==    still reachable: 33,131 bytes in 430 blocks
==8482==         suppressed: 0 bytes in 0 blocks
==8482== Rerun with --leak-check=full to see details of leaked memory
==8482== 
==8482== For counts of detected and suppressed errors, rerun with: -v
==8482== Use --track-origins=yes to see where uninitialised values come from
==8482== ERROR SUMMARY: 15 errors from 5 contexts (suppressed: 0 from 0)

Note: Any output relating to libnvidia-glcore can be safely ignored. That is from the proprietary NVIDIA driver leaking video memory, as usual.

This was tested on an x86_64 Arch Linux machine using GCC 4.9.2 20150304 (prerelease).
Comment 1 Ryan C. Gordon 2015-03-28 05:54:51 UTC 
This is a (tiny) leak in Xlib, unfortunately.

--ryan.
Comment 2 Ryan C. Gordon 2015-03-28 05:56:07 UTC 
(In reply to Ryan C. Gordon from comment #1)
> This is a (tiny) leak in Xlib, unfortunately.

Um, sorry, not a leak. I meant a memory access bug.

--ryan.