linux-kernel - Re: [PATCH] mm: cma: Fix potential null dereference on pointer cma

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Message-ID: <YFD0S7M96jVFVPe+@google.com>
Date:   Tue, 16 Mar 2021 11:09:15 -0700
From:   Minchan Kim <minchan@...nel.org>
To:     Colin King <colin.king@...onical.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        John Hubbard <jhubbard@...dia.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-mm@...ck.org, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: cma: Fix potential null dereference on pointer cma

On Tue, Mar 16, 2021 at 10:04:33AM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> At the start of the function there is a null pointer check on cma
> and then branch to error handling label 'out'.  The subsequent call
> to cma_sysfs_fail_pages_count dereferences cma, hence there is a
> potential null pointer deference issue.  Fix this by only calling
> cma_sysfs_fail_pages_count if cma is not null.
> 
> Addresses-Coverity: ("Dereference after null check")
> Fixes: dc4764f7e9ac ("mm: cma: support sysfs")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
Acked-by: Minchan Kim <minchan@...nel.org>