Created attachment 1242291 [details]
C translation of Rust's env-funky-keys.rs

Description of problem:
Rust builds are hanging in %check on test rust-pass/env-funky-keys.
https://github.com/rust-lang/rust/blob/master/src/test/run-pass/env-funky-keys.rs

I can also hang with a similar program written in C, attached, so let's focus on that.  The same binary copied to F25 runs fine.

Version-Release number of selected component (if applicable):
glibc-2.24.90-28.fc26

How reproducible:
100%

Steps to Reproduce:
1. gcc env-funky-keys.c
2. ./a.out

Actual results:
The program execs and then never terminates -- never even reaches main.

Expected results:
The program should exec and then main should return 0.

Additional info:

Stepping 'next' in gdb just bounces between dl-tunables.c:86 and :90.

(gdb) bt
#0  get_next_env (val=<synthetic pointer>, namelen=<synthetic pointer>,
    name=<synthetic pointer>, envp=0x7fffffffee40) at dl-tunables.c:86
#1  __tunables_init (envp=0x7fffffffee40) at dl-tunables.c:317
#2  0x00007ffff7df0d53 in _dl_sysdep_start (
    start_argptr=start_argptr@entry=0x7fffffffee20,
    dl_main=dl_main@entry=0x7ffff7dd8b10 <dl_main>) at ../elf/dl-sysdep.c:224
#3  0x00007ffff7ddc0b8 in _dl_start_final (arg=0x7fffffffee20) at rtld.c:303
#4  _dl_start (arg=0x7fffffffee20) at rtld.c:409
#5  0x00007ffff7dd7e58 in _start () from /lib64/ld-linux-x86-64.so.2
#6  0x0000000000000002 in ?? ()
#7  0x00007fffffffefa0 in ?? ()
#8  0x00007fffffffefbb in ?? ()
#9  0x0000000000000000 in ?? ()
(gdb) list 81,98
81        while (envp != NULL && *envp != NULL)
82          {
83            char *envline = *envp;
84            int len = 0;
85
86            while (envline[len] != '\0' && envline[len] != '=')
87              len++;
88
89            /* Just the name and no value, go to the next one.  */
90            if (envline[len] == '\0')
91              continue;
92
93            *name = envline;
94            *namelen = len;
95            *val = &envline[len + 1];
96
97            return ++envp;
98          }

It looks to me like the continue is missing ++envp.