Date: Sat, 27 Jul 2013 14:38:20 -0500 From: David Noel <david.i.noel@gmail.com> To: Frank Leonhardt <frank2@fjl.co.uk> Cc: freebsd-questions@freebsd.org Subject: Re: Delete a directory, crash the system Message-ID: <CAHAXwYArUStyGe600oyiYY3oT0rCwYn-UWqedg8%2BCHBPq0ZcUA@mail.gmail.com> In-Reply-To: <51F420ED.1050402@fjl.co.uk> References: <CAHAXwYDPMrdY-TP-5T1_6M_ot4gY09jo2_Wi_REOmE=%2Bu%2B_QuQ@mail.gmail.com> <CAGwOe2byRc4LVsyxvTJgxNGCbhvOEaeDXjmFJ7DoXThPQe1bcQ@mail.gmail.com> <CAHAXwYCj9AV8ZcDffNNGx-ivL=h_TK9zLQRTPknArX25HSfEag@mail.gmail.com> <CAGwOe2YCDRqHudovDB_Kz9WHppvB8v2L%2B0gkDnWgG88bgZTKSA@mail.gmail.com> <CAHAXwYCnRDQqgRcvaEE1BmSJYYOidoQzzUoHX_QWdyJzYO3kKw@mail.gmail.com> <51F3F290.9020004@cordula.ws> <CAHAXwYA7WfYP8OZBVf47xRsDp9N01U3rPLZwwj7PFqkPxm3oag@mail.gmail.com> <51F420ED.1050402@fjl.co.uk>
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> I was going to raise an issue when the discussion had died down to a
> concensus. I also don't think it's reasonable for the kernel to bomb
> when it encounters corruption on a disk.
>
> If you want to patch it yourself, edit sys/ufs/ufs/ufs_vnops.c at around
> line 2791 change:
>
> if (dp->i_effnlink < 3)
> panic("ufs_dirrem: Bad link count %d on parent",
> dp->i_effnlink);
>
> To
>
> if (dp->i_effnlink < 3) {
> error = EINVAL;
> goto out;
> }
>
> The ufs_link() call has a similar issue.
>
> I can't see why my mod will break anything, but there's always
> unintended consequences. By returning invalid argument, any code above
> it should already be handling that condition although the user will be
> scratching their head wondering what's wrong with it. Returning ENOENT
> or EACCES or ENOTDIR may be better ("No such directory", "Access denied"
> or "Not a valid directory").
>
> The trouble is that it's tricky to test properly without finding a good
> way to corrupt the link count :-)
>
> Regards, Frank.
Cool. Thanks for the patch!
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