GNU bug report logs - #79218
BUG: sudo rm -rf /* removes without --no-preserve-root

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Doctorixx <jebpip2008 <at> gmail.com>
To: bug-coreutils <at> gnu.org
Subject: BUG: sudo rm -rf /* removes without --no-preserve-root
Date: Mon, 11 Aug 2025 13:16:04 +0300

[Message part 1 (text/plain, inline)]

Hello coreutils maintainers,

I noticed a potentially dangerous difference in how rm handles the / and /*
patterns.

Currently:

$ sudo rm -rf /
rm: it is dangerous to operate recursively on '/'
rm: use --no-preserve-root to override this failsafe

This prevents accidental deletion of the root directory.

However:

$ sudo rm -rf /*

This command will proceed to remove the contents of /, effectively
destroying the system, without any warning.

While this is technically correct according to shell expansion rules, it
may be surprising for some users. People might assume /* is just as
protected as /, but the safeguard doesn’t apply.

P.S.: I removed root(

[Message part 2 (text/html, inline)]

Message #8 received at 79218 <at> debbugs.gnu.org (full text, mbox):

From: Collin Funk <collin.funk1 <at> gmail.com>
To: Doctorixx <jebpip2008 <at> gmail.com>
Cc: 79218 <at> debbugs.gnu.org
Subject: Re: bug#79218: BUG: sudo rm -rf /* removes without --no-preserve-root
Date: Mon, 11 Aug 2025 08:53:06 -0700

Hi,

Doctorixx <jebpip2008 <at> gmail.com> writes:

> Hello coreutils maintainers,
>
> I noticed a potentially dangerous difference in how rm handles the / and /*
> patterns.
>
> Currently:
>
> $ sudo rm -rf /
> rm: it is dangerous to operate recursively on '/'
> rm: use --no-preserve-root to override this failsafe
>
> This prevents accidental deletion of the root directory.
>
> However:
>
> $ sudo rm -rf /*
>
> This command will proceed to remove the contents of /, effectively
> destroying the system, without any warning.
>
> While this is technically correct according to shell expansion rules, it
> may be surprising for some users. People might assume /* is just as
> protected as /, but the safeguard doesn’t apply.

The 'rm' command does not handle /* since globbing is handled by the
shell. So 'rm' has no way of knowing it is passed /*, it just sees file
names passed to the command-line. Here is an example:

    $ cat main.c 
    #include <stdio.h>
    #include <stdlib.h>
    int
    main (int argc, char **argv)
    {
      for (int i = 1; i < argc; ++i)
        printf ("%s\n", argv[i]);
      return EXIT_SUCCESS;
    }
    $ gcc main.c
    $ ./a.out /*
    /afs
    /bin
    /boot
    /dev
    /etc
    /home
    [...]

Collin

Message #11 received at 79218 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Doctorixx <jebpip2008 <at> gmail.com>, 79218 <at> debbugs.gnu.org
Subject: Re: bug#79218: BUG: sudo rm -rf /* removes without --no-preserve-root
Date: Mon, 11 Aug 2025 17:00:38 +0100

On 11/08/2025 11:16, Doctorixx wrote:
> Hello coreutils maintainers,
> 
> I noticed a potentially dangerous difference in how rm handles the / and /*
> patterns.
> 
> Currently:
> 
> $ sudo rm -rf /
> rm: it is dangerous to operate recursively on '/'
> rm: use --no-preserve-root to override this failsafe
> 
> This prevents accidental deletion of the root directory.
> 
> However:
> 
> $ sudo rm -rf /*
> 
> This command will proceed to remove the contents of /, effectively
> destroying the system, without any warning.
> 
> While this is technically correct according to shell expansion rules, it
> may be surprising for some users. People might assume /* is just as
> protected as /, but the safeguard doesn’t apply.
> 
> P.S.: I removed root(

Unfortunately, rm doesn't see the "/*", it only see's the individual paths,
as the shell does the expansion before executing rm.

A more problematic expansion might be inadvertently adding a space after ~/.
For example if you wanted to `rm -Rf ~/foo/` but instead did `rm -Rf ~/ foo/`.
This is something we could potentially protect against I suppose.

cheers,
Padraig

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