Parts of libcompiler-rt are compiled as WX

[djc]

The following parts have WX sections (that is, memory that is writable and executable at the same time):

 * !WX --- --- usr/lib64/rust-1.9.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler-rt.a:chkstk.o
 * !WX --- --- usr/lib64/rust-1.9.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler-rt.a:chkstk2.o
 * !WX --- --- usr/lib64/rust-1.9.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler-rt.a:floatundidf.o
 * !WX --- --- usr/lib64/rust-1.9.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler-rt.a:floatundisf.o
 * !WX --- --- usr/lib64/rust-1.9.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler-rt.a:floatundixf.o

From a security point of view, this is probably bad.

[trofi]

llikley proper upstream is llvm:
https://github.com/llvm-mirror/compiler-rt/blob/master/lib/builtins/x86_64/chkstk2.S

I suspect it lacks GNU stack marking. Example marking from libffi:
https://github.com/libffi/libffi/blob/master/src/x86/sysv.S#L1038

[Aatch]

Hard to tell if it's an oversight or not from the code. There's a macro that outputs the stack marking if needed, which is used in other files. Either way, this is an upstream issue as it's in compiler-rt.

[Amanieu]

This seems to have been fixed upstream very recently: llvm-mirror/compiler-rt@4c71a47

[alexcrichton]

If this has been fixed upstream, then that's great! The steps for fixing this would then look like:

• Check out the most recent branch of compiler-rt that we're using, which I believe is rust-lang/compiler-rt at the branch rust-2016-06-16
• Cherry-pick the relevant commit to the branch
• Send a PR to the rust-lang/compiler-rt repo on the rust-2016-06-16 branch
• Once merged, send a PR to rust-lang/rust updating the compiler-rt repo
• Ideally write a test as well, but may be somewhat difficult to do that for this...

I'm gonna tag this as E-easy and I'm certainly willing to mentor, if anyone needs any help just let me know!

[apasel422]

Closed in #34647.

[djc]

It seems like this has regressed in 1.14.0:

 * !WX --- --- usr/lib64/rust-1.14.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-f5a209a9.rlib:chkstk.o
 * !WX --- --- usr/lib64/rust-1.14.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-f5a209a9.rlib:chkstk2.o
 * !WX --- --- usr/lib64/rust-1.14.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-f5a209a9.rlib:floatundidf.o
 * !WX --- --- usr/lib64/rust-1.14.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-f5a209a9.rlib:floatundisf.o
 * !WX --- --- usr/lib64/rust-1.14.0/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-f5a209a9.rlib:floatundixf.o