[comp.bugs.sys5] zero length /etc/passwd

wjc@ho5cad.ATT.COM (Bill Carpenter) (04/22/89)

In article <100455@sun.Eng.Sun.COM> plocher%sally@Sun.COM (John Plocher) writes:
> Kids, don't do this at home.
>[shows bug that truncates /etc/passwd]
> 	% ls -l /etc/passwd*
> 	-rw-r--r--  1 root            0 Apr  3 10:44 /etc/passwd
> 	-rw-r--r--  1 root          439 Apr  3 10:40 /etc/passwd.old
> 	% su
> 	password: xxxxxxx
> 	# cp /etc/passwd.old /etc/passwd

No, kidding, "don't do this"!!  I was once the last user on a machine
and discovered that some clever daemon had truncated /etc/passwd.  I
thought I'd do just this sort of thing.  Hmmm, just how did I expect
"su" to verify that I had typed the right passwd?  At least under
SysV, this was big trouble.  Would BSD or SunOS have behaved differently?

"Sorry" (meaning, "grab that backup disk of the root file system").
(I tried being root on machines networked to the damaged one; none let
me get in and most asked personal questions like "Who are you?")
--
--
   Bill Carpenter         att!ho5cad!wjc  or  attmail!bill

plocher%sally@Sun.COM (John Plocher) (04/27/89)

+---- In <WJC.89Apr22100003@ho5cad.ho5cad.ATT.COM> Bill Carpenter writes:
| +---- In <100455@sun.Eng.Sun.COM> John Plocher writes:
| | Kids, don't do this at home.
| |[shows bug that truncates /etc/passwd]
| | 	% su					<<< This will fail   oops  <<<
| | 	password: xxxxxxx
| | 	# cp /etc/passwd.old /etc/passwd
| +----
| No, kidding, "don't do this"!!  I was once the last user on a machine
+----

Wow!  You wouldn't believe how many people caught that one!  That's what
happens when I try to condense the interactions of two terminals into one
without really thinking ;-(  Now back to that full mailbox...

   -John Plocher