linux-kernel - Re: [PATCH v5] kernel: make groups_sort calling a responsibility group

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Message-ID: <20171211152418.GA10521@bombadil.infradead.org>
Date:   Mon, 11 Dec 2017 07:24:18 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Thiago Rafael Becker <thiago.becker@...il.com>
Cc:     viro@...iv.linux.org.uk, schwidefsky@...ibm.com,
        bfields@...ldses.org, neilb@...e.com, linux-nfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] kernel: make groups_sort calling a responsibility
 group_info allocators

On Mon, Dec 11, 2017 at 01:14:20PM -0200, Thiago Rafael Becker wrote:
> In testing, we found that nfsd threads may call set_groups in parallel for
> the same entry cached in auth.unix.gid, racing in the call of groups_sort,
> corrupting the groups for that entry and leading to permission denials for
> the client.
> 
> This patch:
>  - Make groups_sort globally visible.
>  - Move the call to groups_sort to the modifiers of group_info
>  - Remove the call to groups_sort from set_groups
> 
> Signed-off-by: Thiago Rafael Becker <thiago.becker@...il.com>

Reviewed-by: Matthew Wilcox <mawilcox@...rosoft.com>