[UBSAN] Undefined references with -Wl,--no-undefined

[Lastique]

When linking a shared library with -Wl,--no-undefined switch and UBSan enabled, the linking fails with unresolved references to UBSan symbols.

Here's a test case:

ubsan_unresolved_test.cpp:

int test(int n)
{
    return n + 10;
}

Commands:

clang++ -stdlib=libc++ -fsanitize=undefined -fno-sanitize-recover=undefined -o ubsan_unresolved_test.o -c ubsan_unresolved_test.cpp
clang++ -stdlib=libc++ -fsanitize=undefined -fuse-ld=gold -Wl,--no-undefined -shared -o ubsan_unresolved_test.so ubsan_unresolved_test.o

Output:

ubsan_unresolved_test.o:ubsan_unresolved_test.cpp:function test(int): error: undefined reference to '__ubsan_handle_add_overflow_abort'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Clang version:

$ clang -v
Ubuntu clang version 14.0.0-1ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Candidate multilib: .;@m64
Selected multilib: .;@m64

This is on Kubuntu 22.04, x86-64.

The workaround is to add -lubsan to the linker command line.

[EugeneZelenko]

Isn't this gold problem?

[Lastique]

I'm assuming it is the clang driver that is responsible for adding UBSAN libraries to the gold command line.

Also, I should note that the problem does not reproduce with gcc 11.3 on the same system. It also uses gold.

[llvmbot]

@llvm/issue-subscribers-clang-driver

When linking a shared library with `-Wl,--no-undefined` switch and UBSan enabled, the linking fails with unresolved references to UBSan symbols.

Here's a test case:

ubsan_unresolved_test.cpp:

int test(int n)
{
    return n + 10;
}

Commands:

clang++ -stdlib=libc++ -fsanitize=undefined -fno-sanitize-recover=undefined -o ubsan_unresolved_test.o -c ubsan_unresolved_test.cpp
clang++ -stdlib=libc++ -fsanitize=undefined -fuse-ld=gold -Wl,--no-undefined -shared -o ubsan_unresolved_test.so ubsan_unresolved_test.o

Output:

ubsan_unresolved_test.o:ubsan_unresolved_test.cpp:function test(int): error: undefined reference to '__ubsan_handle_add_overflow_abort'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Clang version:

$ clang -v
Ubuntu clang version 14.0.0-1ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Candidate multilib: .;@<!-- -->m64
Selected multilib: .;@<!-- -->m64

This is on Kubuntu 22.04, x86-64.

The workaround is to add -lubsan to the linker command line.