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--strip-unneeded libc.a causes Rust programs compiled with -C target-feature=+crc-static to segfault on startup

Xi Ruoyao xry111@xry111.site
Wed Aug 20 09:34:06 GMT 2025 
Hi,

With the latest Glibc and Binutils release, we found stripping libc.a
with --strip-unneeded will cause any Rust programs compiled with -C
target-feature=+crc-static (i.e. linking against the static libc) to
segfault on startup.  To reproduce:

$ cat hw.rs
pub fn main() {
    println!("Hello, world.");
}
$ unshare -mr env PS1="(unshared ns)# " LC_ALL=C bash --norc
(unshared ns)# cp /usr/lib/libc.a /tmp
(unshared ns)# strip --strip-unneeded /tmp/libc.a
(unshared ns)# mount --bind /tmp/libc.a /usr/lib/libc.a
(unshared ns)# rustc hw.rs -C target-feature=+crt-static
(unshared ns)# ./hw
Segmentation fault         (core dumped) ./hw
(unshared ns)# gdb hw
(gdb) r
Starting program: /home/xry111/hw 

Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00007ffff7f507a3 in _IO_doallocbuf ()
#2  0x00007ffff7f4d756 in _IO_new_file_underflow ()
#3  0x00007ffff7f4b313 in getdelim ()
#4  0x00007ffff7f169da in pthread_getattr_np ()
#5  0x00007ffff7ef28f6 in std::rt::lang_start_internal ()
#6  0x00007ffff7ed8911 in std::rt::lang_start ()
#7  0x00007ffff7ed8a45 in main ()

We are currently working the issue around by using --strip-debug instead
of --strip-unneeded, but this seems bizarre to me: shouldn't --strip-
unneeded just keep anything that the linker may "need" to create a
correct executable?  Or is Glibc or Rust std doing something so strange
that strip cannot really tell it's needed?

-- 
Xi Ruoyao <xry111@xry111.site>
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