ASAN: Overlapping memcpy() in scroll_default() when running surface_test

[cgutman]

Running pygame.tests.surface_test under AddressSanitizer reports an illegal overlapping memcpy() in scroll_default() which was introduced in #2855. It seems like some of the new memcpy() invocations introduced there need to be changed to memmove() like the old implementation had.

=================================================================
==172097==ERROR: AddressSanitizer: memcpy-param-overlap: memory ranges [0x515000412b20,0x515000412b32) and [0x515000412b22, 0x515000412b34) overlap
    #0 0x72eac26fad46 in memcpy /usr/src/debug/gcc/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors_memintrinsics.inc:115
    #1 0x72eabf39f9d2 in scroll_default ../src_c/surface.c:2522
    #2 0x72eabf39f9d2 in scroll ../src_c/surface.c:2554
    #3 0x72eabf39f9d2 in surf_scroll ../src_c/surface.c:2635
    #4 0x72eac2197c97  (/usr/lib/libpython3.13.so.1.0+0x197c97) (BuildId: 31a24ec0805217755810c6e20886eb3260a0a6d3)
    #5 0x72eac215f82c in PyObject_Vectorcall (/usr/lib/libpython3.13.so.1.0+0x15f82c) (BuildId: 31a24ec0805217755810c6e20886eb3260a0a6d3)
    #6 0x72eac216f306 in _PyEval_EvalFrameDefault (/usr/lib/libpython3.13.so.1.0+0x16f306) (BuildId: 31a24ec0805217755810c6e20886eb3260a0a6d3)
[snip]

0x515000412b20 is located 32 bytes inside of 456-byte region [0x515000412b00,0x515000412cc8)
allocated by thread T0 here:
    #0 0x72eac26fd721 in malloc /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:69
    #1 0x72eabb50c636 in real_malloc /home/cgutman/SDL/src/stdlib/SDL_malloc.c:6327
    #2 0x72eabb50cae8 in SDL_malloc_REAL /home/cgutman/SDL/src/stdlib/SDL_malloc.c:6452
    #3 0x72eabb5155ea in SDL_aligned_alloc_REAL /home/cgutman/SDL/src/stdlib/SDL_stdlib.c:546
    #4 0x72eabb86f2f9 in SDL_CreateSurface_REAL /home/cgutman/SDL/src/video/SDL_surface.c:229
    #5 0x72eabb0d799c in SDL_CreateSurface /home/cgutman/SDL/src/dynapi/SDL_dynapi_procs.h:153
    #6 0x72eabe2e6656 in SDL_CreateRGBSurfaceWithFormat_REAL /home/cgutman/sdl2-compat/src/sdl2_compat.c:4277
    #7 0x72eabe3388f0 in SDL_CreateRGBSurfaceWithFormat /home/cgutman/sdl2-compat/src/dynapi/SDL_dynapi_procs.h:631
    #8 0x72eabf3a1877 in surface_init ../src_c/surface.c:670
    #9 0x72eac216ecd3 in _PyEval_EvalFrameDefault (/usr/lib/libpython3.13.so.1.0+0x16ecd3) (BuildId: 31a24ec0805217755810c6e20886eb3260a0a6d3)
[snip]

0x515000412b22 is located 34 bytes inside of 456-byte region [0x515000412b00,0x515000412cc8)
allocated by thread T0 here:
    #0 0x72eac26fd721 in malloc /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:69
    #1 0x72eabb50c636 in real_malloc /home/cgutman/SDL/src/stdlib/SDL_malloc.c:6327
    #2 0x72eabb50cae8 in SDL_malloc_REAL /home/cgutman/SDL/src/stdlib/SDL_malloc.c:6452
    #3 0x72eabb5155ea in SDL_aligned_alloc_REAL /home/cgutman/SDL/src/stdlib/SDL_stdlib.c:546
    #4 0x72eabb86f2f9 in SDL_CreateSurface_REAL /home/cgutman/SDL/src/video/SDL_surface.c:229
    #5 0x72eabb0d799c in SDL_CreateSurface /home/cgutman/SDL/src/dynapi/SDL_dynapi_procs.h:153
    #6 0x72eabe2e6656 in SDL_CreateRGBSurfaceWithFormat_REAL /home/cgutman/sdl2-compat/src/sdl2_compat.c:4277
    #7 0x72eabe3388f0 in SDL_CreateRGBSurfaceWithFormat /home/cgutman/sdl2-compat/src/dynapi/SDL_dynapi_procs.h:631
    #8 0x72eabf3a1877 in surface_init ../src_c/surface.c:670
    #9 0x72eac216ecd3 in _PyEval_EvalFrameDefault (/usr/lib/libpython3.13.so.1.0+0x16ecd3) (BuildId: 31a24ec0805217755810c6e20886eb3260a0a6d3)
[snip]

SUMMARY: AddressSanitizer: memcpy-param-overlap /usr/src/debug/gcc/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors_memintrinsics.inc:115 in memcpy
==172097==ABORTING

Environment:
pygame-ce commit: 0510571

pygame-ce 2.5.4.dev1 (SDL 2.32.55, Python 3.13.3)
Platform:               Linux-6.14.3-arch1-1-x86_64-with-glibc2.41
System:                 Linux
System Version:         #1 SMP PREEMPT_DYNAMIC Sun, 20 Apr 2025 12:38:52 +0000
Processor:                      SSE2: Yes       AVX2: No        NEON: No
Architecture:           Bits: 64bit     Linkage: ELF

Python:                 CPython 3.13.3 (main, Apr  9 2025, 07:44:25) [GCC 14.2.1 20250207]
GIL Enabled:            True
pygame version:         2.5.4.dev1
SDL versions:           Linked: 2.32.55 Compiled: 2.32.55
SDL Mixer versions:     Linked: 2.8.1   Compiled: 2.8.1
SDL Font versions:      Linked: 2.24.0  Compiled: 2.24.0
SDL Image versions:     Linked: 2.8.8   Compiled: 2.8.8
Freetype versions:      Linked: 2.13.3  Compiled: 2.13.3

Display Driver:         Display Not Initialized
Mixer Driver:           Mixer Not Initialized

[damusss]

Oh my my I'm the culprit!
(I'll check properly later I'm not home)

[damusss]

@cgutman I've committed the change from memcpy to memmove in this branch: https://github.com/damusss/pygame-ce/tree/fix-memmove-scroll , are you able to clone it, build it and run the sanitizer again? Can you also tell me if the same overlapping issue occurs for scroll_repeat? Thank you

[ankith26]

I have made a PR that fixes the issue, the fixes from damus's branch weren't sufficient