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Date:   Thu, 31 Aug 2023 14:36:19 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Christian Brauner <brauner@kernel.org>
Cc:     Christoph Hellwig <hch@lst.de>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
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        Eric Paris <eparis@parisplace.org>, linux-s390@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, selinux@vger.kernel.org
Subject: Re: sb->s_fs_info freeing fixes
Message-ID: <20230831123619.GB11156@lst.de>
References: <20230831053157.256319-1-hch@lst.de> <20230831-dazulernen-gepflanzt-8a64056bf362@brauner> <20230831-tiefbau-freuden-3e8225acc81d@brauner>
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On Thu, Aug 31, 2023 at 12:29:11PM +0200, Christian Brauner wrote:
> "Since ramfs/devpts uses get_tree_nodev() it doesn't rely on
> sb->s_fs_info. So there's no use after free risk as with other
> filesystems.
> 
> But there's no need to deviate from the standard cleanup logic and cause
> reviewers to verify whether that is safe or not."
> 
> and similar for the other two:
> 
> "Since hypfs/selinuxfs uses get_tree_single() it doesn't rely on
> sb->s_fs_info. So there's no use after free risk as with other
> filesystems.
> 
> But there's no need to deviate from the standard cleanup logic and cause
> reviewers to verify whether that is safe or not."
> 
> If that is good enough for people then I can grab it.

Fine with me.  And yes, I'd rather not have private data freed before
SB_ACTIVE is cleared even if it is fine right now.  It's just a bug
waiting to happen.