Bash leaks memory when doing function calls while reading from subshell as stdin

[Øyvind Hvidsten]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' 
-DSHELL -DHAVE_CONFIG_H   -I.  -I../. -I.././include -I.././lib 
-Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 
-fdebug-prefix-map=/build/bash-7fckc0/bash-4.4=. 
-fstack-protector-strong -Wformat -Werror=format-security -Wall -no-pie 
-Wno-parentheses -Wno-format-security
uname output: Linux vampiric 4.9.0-4-amd64 #1 SMP Debian 4.9.51-1 
(2017-09-28) x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.4
Patch Level: 12
Release Status: release

Description:
	Somehow the included script causes a memory leak. Memory usage will 
grow huge over a very short timeframe.
	The script is pointless, but cut down from a larger one that does 
something useful.
	Originally, the subshell was reading a while (cat ...), so the printf 
loop has nothing to do with it.
	Replacing the call to f2() with an echo, or anything not a function 
call, makes it not leak.

Repeat-By:
        f2() { return 1; }
        f1()
        {
            while read -r line; do
                f2 "test"
            done < <(
                for ((i=0;i<1000000000;i++)); do
                    printf '%s\n' "$i"
                done
            )
        }
        
        f1