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-redhat-linux-gnu'
-DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale'
-DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -I. -I. -I./include
-I./lib -D_GNU_SOURCE -DRECYCLES_PIDS
-DDEFAULT_PATH_VALUE='/usr/local/bin:/usr/bin' -O2 -g -pipe -Wall
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong
--param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic
uname output: Linux server1 3.10.0-327.18.2.el7.x86_64 #1 SMP Fri Apr
8 05:09:53 EDT 2016 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-redhat-linux-gnu
Bash Version: 4.2
Patch Level: 46
Release Status: release
Description:
Bash history / reverse-i-search will execute the command found
if the ssh process is killed.
This happens with the combination of:
- ssh into server
- sudo su -
- reverse-i-search # <ctrl>+R
I.e. a user in the middle of a bash reverse-i-search, and the
ssh process is killed
i.e. due to a network outage.
This can be critical if the command in the search history is
something harmful or potentially unwanted, like a server shutdown
The chain of events during the kill, and how the sub processes
are killed might be the cause here, but nevertheless no signal
should cause the bash history command to run.
Repeat-By:
Pre-requisites: a user with a bash shell
Log (SSH) in to a server (server1)
On server1 type
date > /tmp/file.txt
rm /tmp/file.txt
On server1 type
<ctrl>+R "date"
Log in to server1 on a second terminal / ssh window
ps -ef | grep <sshd@pty-of-first-login>
kill <pid-of-sshd-process-for-first-login>
ls -l /tmp/file.txt
The /tmp/file.txt has now been created
Verified on (also):
Ubuntu 16.04 LTS
================
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 $
uname output: Linux ubuntu1604 4.4.0-43-generic #63-Ubuntu SMP
Wed Oct 12 13:48:03 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu
Bash Version: 4.3
Patch Level: 46
Release Status: release
Bash Version: 4.3 Patch Level: 46 Release Status: release
CentOS Linux release 7.2.1511 (Core)
===========
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-redhat-linux-gnu'
-DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale'
-DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -I. -I. -I./include
-I./lib -D_GNU_SOURCE -DRECYCLES_PIDS
-DDEFAULT_PATH_VALUE='/usr/local/bin:/usr/bin' -O2 -g -pipe -Wall
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong
--param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic
uname output: Linux centos7 3.10.0-327.22.2.el7.x86_64 #1 SMP
Thu Jun 23 17:05:11 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-redhat-linux-gnu
Bash Version: 4.2
Patch Level: 46
Release Status: release
Unable to reproduce with:
- Local gnome terminal + bash in ubuntu
- ssh to a user in two terminals, repeat steps and kill the
second terminal
It seems that there is something happening when killing the
sshd process in combination with sudo
--
Stein Arne Storslett
