Date: Sat, 27 Jul 2013 20:43:23 +0100 From: Frank Leonhardt <frank2@fjl.co.uk> To: freebsd-questions@freebsd.org Subject: Re: Delete a directory, crash the system Message-ID: <51F422DB.2000205@fjl.co.uk> In-Reply-To: <CAHAXwYArUStyGe600oyiYY3oT0rCwYn-UWqedg8%2BCHBPq0ZcUA@mail.gmail.com> 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> <CAHAXwYArUStyGe600oyiYY3oT0rCwYn-UWqedg8%2BCHBPq0ZcUA@mail.gmail.com>
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On 27/07/2013 20:38, David Noel wrote:
>> 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!
>
Sorry - forgot to mention that you use it entirely at your own risk!
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