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Wong" , Alex Deucher , David Hildenbrand , Kuninori Morimoto , Kairui Song , Myeonghun Pak , Rafal Ostrowski , Likun Gao , James Clark , Anshuman Khandual , Kevin Brodsky , linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] xfs: fix out-of-bounds write from crafted btree root numrecs during log recovery Message-ID: References: <20261027151703.973392-1-bsdhenrymartin@gmail.com> <87cxsto38m.fsf@trenco.lwn.net> X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Oct 29, 2026 at 10:34:44AM -0500, Dave Chinner wrote: > These aren't security bugs. Bugs that result from maliciously > corrupted filesystem images (i.e. fuzzed) are explicitly stated as > not covered by the kernel security threat models. IOWs, they are > just -bugs-, and bugs that just don't ever happen in the real world. Well, there are people/companies who might be silly/stupid enough to think that containers are a real security isolation layer[1], and who think that they can let random users mount untrusted file systems in a container, and not have to worry about one company gaining access to PII belonging to another company because both companies are using a particular cloud hosting provider which uses containers and allows their customers to mount file systems as (container) root, with multiple customers sharing the some physical host. As Dave has said, *all* of the file system maintainers have explicitly disclaimed this security model; from our perspective the block device is inside the trusted computing base (TCB), and if someone wants to dedicaste one or more full-time engineers to be file system developers who have contributed a large number of improvements to the file system, and who understand the context that they can competently drive LLM's to create architecturally sound patches, I *might* be willing to change my stance for ext4. But those hosting providers' engineers would have do most of the work to try to make this security model work --- and it might be that using fuse2fs, and running that fuse server in a sandbox (e.g. seccomp-bpf, etc.) might be a much simpler / cheaper solution in the end. Cheers, - Ted [1] There's a *reason* why Google Kubernetes Engine (GKE) uses VM's and not containers as a security isolation layer. :-)