sysrc (awk) bug

[mario at supermoder.si]

To my knowledge, it is not recommended to change default shell. As for rest I will leave to other experts. 

https://docs.freebsd.org/en/articles/linux-users/#shells


Regards,
Mario


> On 30 May 2021, at 06:36, Fas Xmut via freebsd-security <freebsd-security at freebsd.org> wrote:
> 
> I don't know if it is a security bug or not. When I use sysrc today, the error operations emptied my /etc/rc.conf, that's a small disaster, because my /etc/rc.conf is updated day by day, but now, it is empty.
> 
> First, change your default root shell to sh/ksh or their derived shell. (I have tested, csh will not trigger that bug).
> 
> Second, backup /etc/rc.conf to any other place.
> 
> Then do the following commands:
> 
> ------------------------------------------------------------------------
> # sysrc something_enable="NO"
> # sysrc something_enable="YES
>> "
> awk: newline in string YES
> ... at source line 1
> something_enable: NO -> YES
> ------------------------------------------------------------------------
> 
> Now see what is inside /etc/rc.conf ? Everything is empty! only one thing in it:
> 
> ------------------------------------------------------------------------
> something_enable="YES
> "
> ------------------------------------------------------------------------
> 
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