Re: Bash crashes on detaching Screen

[Darshit Shah]

On 12/02, Darshit Shah wrote:
> I use GNU Screen along with Bash for my SSH sessions.
>
> While detaching my Screen sessions I came across a weird Bash bug and 
> I'd like your help in debugging this issue.
>
> When I attempt to detach a running Screen session using `screen -Drr 
> ,session name` command, the original shell which contained the screen 
> session does not return to a prompt. It instead remains hung and a 
> while later I get the message:
>
> Warning: Program '/bin/bash' crashed
>
> I'm running Arch Linux with Bash 4.3.30(1) and Konsole. I attempted to 
> detach and reattach a screen session from Terminator and did not 
> experience any crashes in Bash.
>
> However, when I attempted the same from a virtual Terminal instead of 
> an emulator, upon remotely detaching the screen session, my terminal 
> directly displayed a login prompt again. This leads me to believe that 
> Bash did crash even then and caused the login prompt to reappear.

I just recompiled my Bash with debugging symbols and attempted to run Bash under 
gdb. Here is the trace I received:


[remote power detached from 19442.pts-1.mordor]

Program received signal SIGHUP, Hangup.
0x00007ffff743b58a in waitpid () from /usr/lib/libc.so.6
(gdb) bt
#0  0x00007ffff743b58a in waitpid () from /usr/lib/libc.so.6
#1  0x000000000043dcfe in waitchld (block=block@entry=1, wpid=16581) at 
jobs.c:3224
#2  0x000000000043efc3 in wait_for (pid=16581) at jobs.c:2485
#3  0x000000000042fc21 in execute_command_internal (command=0x7eec10, 
asynchronous=0, pipe_in=-1, pipe_out=-255, fds_to_close=0x7d3920) at 
execute_cmd.c:829
#4  0x000000000042fdce in execute_command (command=0x7eec10) at 
execute_cmd.c:390
#5  0x000000000042e16d in execute_if_command (if_command=<optimized out>) at 
execute_cmd.c:3430
#6  execute_command_internal (command=0x7eeaf0, asynchronous=8317728, 
pipe_in=-1, pipe_out=365, fds_to_close=0x6f9fb0) at execute_cmd.c:897
#7  0x000000000042e78f in execute_connection (fds_to_close=<optimized out>, pipe_out=<optimized out>, pipe_in=<optimized out>, asynchronous=<optimized out>, 
   command=<optimized out>) at execute_cmd.c:2496
#8  execute_command_internal (command=0x7a5e20, asynchronous=0, pipe_in=-1, 
pipe_out=-1, fds_to_close=0x6f9fb0) at execute_cmd.c:945
#9  0x000000000042e0d9 in execute_command_internal (command=0x6fa110, 
asynchronous=0, pipe_in=-1, pipe_out=-1, fds_to_close=0x6f9fb0) at 
execute_cmd.c:937
#10 0x0000000000431310 in execute_function (var=var@entry=0x7c9970, flags=flags@entry=0, fds_to_close=fds_to_close@entry=0x6f9fb0, async=async@entry=0, 
   subshell=subshell@entry=0, words=<optimized out>) at execute_cmd.c:4539
#11 0x000000000042d769 in execute_builtin_or_function (flags=0, 
fds_to_close=0x6f9fb0, redirects=<optimized out>, var=0x7c9970, builtin=0x0, 
words=0x7d4ff0)
   at execute_cmd.c:4769
#12 execute_simple_command (simple_command=<optimized out>, pipe_in=-1, 
pipe_out=-1, async=0, fds_to_close=0x6f9fb0) at execute_cmd.c:4170
#13 0x000000000042e5ff in execute_command_internal (command=0x7eae20, 
asynchronous=0, pipe_in=-1, pipe_out=-1, fds_to_close=0x6f9fb0) at 
execute_cmd.c:787
#14 0x000000000042fdce in execute_command (command=0x7eae20) at 
execute_cmd.c:390
#15 0x000000000041aa9e in reader_loop () at eval.c:160
#16 0x000000000041933e in main (argc=1, argv=0x7fffffffe4e8, 
env=0x7fffffffe4f8) at shell.c:755



Do let me know if there's any other way in which I can help in debugging this 
issue.

--
Thanking You,
Darshit Shah

pgpejwhJoqnd4.pgp
Description: PGP signature