Re: expand_prompt_string segmentation faults

[Eduardo A . Bustamante López]

Here's another interesting crash:

$ base64 < 53
MBgFEBAQMBgFEBAfEA==

$ gdb -batch -ex=r -ex=bt --args ./bash --noprofile --norc -c 'PATH=; set -o 
emacs; IFS= read -re' < 53
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0
[Detaching after fork from child process 30991]
/home/dualbus/src/gnu/bash/bash: vim: No such file or directory
0
[Detaching after fork from child process 30992]
/home/dualbus/src/gnu/bash/bash: vim: No such file or directory

malloc: unknown:0: assertion botched
malloc: 0x630808: allocated: last allocated from unknown:0
free: called with already freed block argument
Aborting...
Program received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
50      ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1  0x00007ffff79a7535 in __GI_abort () at abort.c:79
#2  0x00000000004597bb in programming_error (format=0x5557be "free: called with 
already freed block argument") at error.c:175
#3  0x00000000005322c2 in xbotch (mem=0x630808, e=1, s=0x5557be "free: called 
with already freed block argument", file=0x0, line=0) at malloc.c:354
#4  0x000000000053155c in internal_free (mem=0x630808, file=0x0, line=0, 
flags=0) at malloc.c:931
#5  0x0000000000531d4f in free (mem=0x630808) at malloc.c:1388
#6  0x00000000004b5150 in xfree (string=0x630808) at xmalloc.c:150
#7  0x000000000051e94c in rl_do_undo () at undo.c:240
#8  0x000000000051eb23 in rl_revert_line (count=1, key=0) at undo.c:312
#9  0x00000000004fa7f9 in readline_internal_teardown (eof=1) at readline.c:471
#10 0x00000000004fa591 in readline_internal () at readline.c:672
#11 0x00000000004fa440 in readline (prompt=0x55466f "") at readline.c:377
#12 0x00000000004caa16 in edit_line (p=0x55466f "", itext=0x0) at 
./read.def:1104
#13 0x00000000004c94ba in read_builtin (list=0x0) at ./read.def:563
#14 0x000000000044b599 in execute_builtin (builtin=0x4c8560 <read_builtin>, 
words=0x628f88, flags=0, subshell=0) at execute_cmd.c:4677
#15 0x000000000044a96f in execute_builtin_or_function (words=0x628f88, 
builtin=0x4c8560 <read_builtin>, var=0x0, redirects=0x0, fds_to_close=0x628ce8, 
flags=0) at execute_cmd.c:5185
#16 0x00000000004437c9 in execute_simple_command (simple_command=0x628c08, 
pipe_in=-1, pipe_out=-1, async=0, fds_to_close=0x628ce8) at execute_cmd.c:4449
#17 0x00000000004412ab in execute_command_internal (command=0x628bc8, 
asynchronous=0, pipe_in=-1, pipe_out=-1, fds_to_close=0x628ce8) at 
execute_cmd.c:840
#18 0x0000000000445208 in execute_connection (command=0x628d48, asynchronous=0, 
pipe_in=-1, pipe_out=-1, fds_to_close=0x628ce8) at execute_cmd.c:2689
#19 0x0000000000441681 in execute_command_internal (command=0x628d48, 
asynchronous=0, pipe_in=-1, pipe_out=-1, fds_to_close=0x628ce8) at 
execute_cmd.c:1013
#20 0x00000000004bf527 in parse_and_execute (string=0x628408 "PATH=; set -o 
emacs; IFS= read -re", from_file=0x5353fb "-c", flags=4) at evalstring.c:436
#21 0x0000000000423845 in run_one_command (command=0x7fffffffea92 "PATH=; set 
-o emacs; IFS= read -re") at shell.c:1416
#22 0x0000000000421920 in main (argc=5, argv=0x7fffffffe758, 
env=0x7fffffffe788) at shell.c:735


Bash compiled with:

`CC=clang CFLAGS='-O0 -ggdb' ./configure && make -j4' from `devel' 
(b52e30b8dd5bba5aed7b13040c9d4f7a0c1990cc) on Linux
(Ubuntu 18.04)