Re: Linux 4.2-rc1

[Casey Schaufler <casey@xxxxxxxxxxxxxxxx>]

On 7/8/2015 11:07 AM, William Roberts wrote:

On Wed, Jul 8, 2015 at 10:47 AM, Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote:

On 7/8/2015 10:29 AM, Linus Torvalds wrote:
> On Wed, Jul 8, 2015 at 10:17 AM, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>> Decoding the "Code:" line shows that this is the "->fw_id" dereference in
>>
>>         if (add_uevent_var(env, "FIRMWARE=%s", fw_priv->buf->fw_id))
>>                 return -ENOMEM;
>>
>> and that "fw_priv->buf" pointer is NULL.
>>
>> However, I don't see anything that looks like it should have changed
>> any of this since 4.1.
> Looking at the otehr uses of "fw_priv->buf", they all check that
> pointer for NULL. I see code like
>
>         fw_buf = fw_priv->buf;
>         if (!fw_buf)
>                 goto out;
>
> etc.
>
> Also, it looks like you need to hold the "fw_lock" to even look at
> that pointer, since the buffer can get reallocated etc.
>
> So that uevent code really looks buggy. It just doesn't look like a
> *new* bug to me. That code looks old, going back to 2012 and commit
> 1244691c73b2.

There have been SELinux changes to kernfs for 4.2. William,
you might want to have a look here.

My changes were never merged AFAIK and can tell. I was still working on this

but we had some changes internally to SELinux that let us handle this, although

we should correct this on kernfs at some point, its low priority for me now. Also

commit fb029 makes kernfs_get_inode() public, so I need to rethink some things.

OK, false alarm. Not an SELinux issue. It might be useful
to see if the problem occurs with AppArmor off.

 

>
> Ming Lei?
>
>                  Linus
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--

Respectfully,

William C Roberts

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