[Pkg-rust-maintainers] Bug#953648: bindgen: segfault on powerpc

[Daniel Kahn Gillmor]

Package: bindgen
Version: 0.51.1-4
X-Debbugs-Cc: Justus Winter <teythoon at avior.uberspace.de>
Control: affects -1 src:rust-nettle-sys

On perotto.debian.net (the powerpc porter box), i'm in a 32-bit powerpc
chroot experimenting with bindgen.

I get a segfault that i can't account for when trying to generate an
extremely minimal binding:

    void i_am_looking_at_the(void);


```
(sid_powerpc-dchroot)dkg at perotto:~/src/bindgen-test$ echo 'void i_am_looking_at_the(void);' > void.h
(sid_powerpc-dchroot)dkg at perotto:~/src/bindgen-test$ ulimit -c 10000000
(sid_powerpc-dchroot)dkg at perotto:~/src/bindgen-test$ bindgen void.h
Segmentation fault (core dumped)
(sid_powerpc-dchroot)dkg at perotto:~/src/bindgen-test$ gdb -c core $(which bindgen)
GNU gdb (Debian 9.1-2) 9.1
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
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Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
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Reading symbols from /usr/bin/bindgen...
Reading symbols from /usr/lib/debug/.build-id/de/e00c8c6783edceb776638570fde91cededf1ba.debug...
[New LWP 41431]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/powerpc-linux-gnu/libthread_db.so.1".
bt
Core was generated by `bindgen void.h'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  strlen () at ../sysdeps/powerpc/powerpc32/strlen.S:98
98	../sysdeps/powerpc/powerpc32/strlen.S: No such file or directory.
warning: Missing auto-load script at offset 0 in section .debug_gdb_scripts
of file /usr/bin/bindgen.
Use `info auto-load python-scripts [REGEXP]' to list them.
(gdb) bt
#0  strlen () at ../sysdeps/powerpc/powerpc32/strlen.S:98
#1  0x00d337fc in std::ffi::c_str::CStr::from_ptr ()
#2  0x00b641a0 in bindgen::clang::cxstring_to_string_leaky (s=...) at src/clang.rs:1476
#3  bindgen::clang::cxstring_into_string (s=...) at src/clang.rs:1481
#4  bindgen::clang::extract_clang_version () at src/clang.rs:1925
#5  0x00ba14bc in bindgen::clang_version () at src/lib.rs:2121
#6  0x00aa2554 in bindgen::main () at src/main.rs:26
(gdb) up
#1  0x00d337fc in std::ffi::c_str::CStr::from_ptr ()
(gdb) up
#2  0x00b641a0 in bindgen::clang::cxstring_to_string_leaky (s=...) at src/clang.rs:1476
1476	    let c_str = unsafe { CStr::from_ptr(clang_getCString(s) as *const _) };
(gdb) print s
$1 = clang_sys::CXString {data: 0x143bef0, private_flags: 1}
(gdb) printf "%s\n", s.data
clang version 9.0.1-9 
(gdb) quit
(sid_powerpc-dchroot)dkg at perotto:~/src/bindgen-test$
```

Weirdly, i note that i see no arguments for strlen at all in the backtrace here :/

I don't know where to get the debug symbols for
std::ffi::c_str::CStr::from_ptr either.

I note that this has no problems running on x86-64.

Any suggestions are welcome!

I ran into this while debugging a failing powerpc build for nettle-sys,
which you can see here:

https://gitlab.com/sequoia-pgp/nettle-sys/-/issues/8

Regards,

         --dkg
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