linux-kernel - Re: RDMA: Clean destroy CQ in drivers do not return errors

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Message-ID: <ee0c017e93e28317791b7395e257801a208c7306.camel@redhat.com>
Date:   Fri, 14 Jun 2019 15:46:50 -0400
From:   Doug Ledford <dledford@...hat.com>
To:     Colin Ian King <colin.king@...onical.com>,
        Leon Romanovsky <leonro@...lanox.com>,
        Gal Pressman <galpress@...zon.com>,
        Dennis Dalessandro <dennis.dalessandro@...el.com>,
        linux-rdma@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: RDMA: Clean destroy CQ in drivers do not return errors

On Fri, 2019-06-14 at 14:59 +0100, Colin Ian King wrote:
> Hi,
> 
> Static analysis with Coverity reported an issue with the following
> commit:
> 
> commit a52c8e2469c30cf7ac453d624aed9c168b23d1af
> Author: Leon Romanovsky <leonro@...lanox.com>
> Date:   Tue May 28 14:37:28 2019 +0300
> 
>     RDMA: Clean destroy CQ in drivers do not return errors
> 
> In function bnxt_re_destroy_cq() contains the following:
> 
>         if (!cq->umem)
>                 ib_umem_release(cq->umem);

Given that the original test that was replaced was:
	if (!IS_ERR_OR_NULL(cq->umem))

we aren't really worried about a null cq, just that umem is valid.  So,
the logic is inverted on the test (or possibly we shouldn't have
replaced !IS_ERR_OR_NULL(cq->umem) at all).

But on closer inspection, the bnxt_re specific portion of this patch
appears to have another problem in that it no longer checks the result
of bnxt_qplib_destroy_cq() yet it does nothing to keep that function
from failing.

Leon, can you send a followup fix?

> Coverity detects this as a deference after null check on the null
> pointer cq->umem:
> 
> "var_deref_model: Passing null pointer cq->umem to ib_umem_release,
> which dereferences it"
> 
> Is the logic inverted on that null check?
> 
> Colin

-- 
Doug Ledford <dledford@...hat.com>
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