Segfault on LoongArch64 (LA64) during init_malloc_hook - GOT entry for real_dlsym is NULL

[ximi-fengzhigu]

Bug Description

box64 crashes with SIGSEGV immediately on startup on LoongArch64 (Loongson-3A5000M, LA64).

Environment

• OS: Kylin Linux V10 SP1 (LoongArch64)
• CPU: Loongson-3A5000M
• gcc version: 8.3.0
• glibc: 2.28
• box64: compiled from source (latest main branch)
• cmake: 3.16.3

Reproduction

Build with default settings on LA64:
mkdir build && cd build
cmake .. -DBOX64_LAZYPATCH=1
make -j$(nproc)
./box64 --version
→ Segmentation fault (core dumped)

Root Cause (GDB analysis)

Crash occurs in init_malloc_hook() at mallochook.c:1085:
box_malloc_usable_size = dlsym(RTLD_NEXT, "malloc_usable_size")

Call stack:
#0 0x0000000000000000 in ?? ()
#1 0x000000003510ed24 in dlsym (handle=0xffffffffffffffff, symbol="malloc_usable_size")
#2 0x000000003498307c in init_malloc_hook () ← mallochook.c:1085
#3 0x000000003483d53c in initialize () ← core.c:776
#4 0x000000003482fd90 in main ()

The handle value 0xffffffffffffffff is correct (RTLD_NEXT).
The crash happens because box64's custom dlsym wrapper calls real_dlsym,
but real_dlsym's GOT entry is NULL at this early initialization stage.

Additional Notes

• Disabling DYNAREC (DLARCH64_DYNAREC=OFF) does not fix it
• STATICBUILD=ON does not fix it
• ARM64 build does not have this issue (different code path)
• The problem is specific to LA64 + DYNAREC combination

[ksco]

cmake .. -DBOX64_LAZYPATCH=1

What is BOX64_LAZYPATCH? Please read docs/COMPILE.md for compile instructions, and you need to enable LARCH64_ABI_1 for old world.

[ptitSeb]

Also, latest Box64 needs CMAKE 3.19+, so I doubt it's latest box64 your are building.

Is this on some OldWorld OS?