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b=fv/XMh+ciNrkinWE2uBqyZ2g/HbLC9pT6uDzbPPDf4mdTgRykf8To4g7xkYKggnZw ADGOc6rhFVqm8fli9Kg6FbxUztl7iIXjjFxXe7c5uqSxWDNZNzPSwlssQE70XaQ2lY E67hvMJX/ROPD8WgGruQCvgAveUmP7zQv+QdGYpk= Date: Fri, 25 Sep 2026 16:04:53 -0700 From: Andrew Morton To: "Lorenzo Stoakes (ARM)" Cc: Anastasios Papagiannis , linux-mm@kvack.org, liam@infradead.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/nommu: Reject wrapping ranges in access_remote_vm() Message-Id: <20260925160453.7e7561edb77b5c4152675f7e@linux-foundation.org> In-Reply-To: References: <20260909064231.18693-1-tasos.papagiannnis@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7E15B40004 X-Stat-Signature: 7m7qnyrccena4dk6p1yfxok637om11im X-Rspam-User: X-HE-Tag: 1790377494-498215 X-HE-Meta: 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 +OnX8c1q UEFqhLh8s+7jprbxfVjapZOKEF4t861O/APc/cMinugjJhJmrR+2xQ6R8PAIHSWqPlYbUIYCyI8OkFXW4vmZbmDORBnQkmhD5pQd1wVdQmV7Swjfs/UcwBqupIb6bsw3FD0XYt2KrRcMKuhU59xabHCu6cNa1C7qFSACXqH5Er4xuXH4NUPVuabsCaX0ufNKG8E7D4NMi5/fRJFL0bxYhwO0kx8Cyo1Zjktkx94UrVkAgjOIuJfMduKRPF9l0mt0GIqxhk1O1Ox67BIohc/G+cQP9AAsiUh7d3g5UQG9xX/1QqxhkmsS58naQAp5cxv6bZqHpAbtg4iCCkl01yQXh/R+VfK5S+CCIwx2QhFYqwdo1unLPBg3fgYLidBxNz0aqLV9QHeZFbu2tJ7mE8d/a2KtAa+RzNP6mSVyJ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 25 Sep 2026 14:20:33 +0100 "Lorenzo Stoakes (ARM)" wrote: > BTW always feel free to nag if you're not getting review! Something things > get missed. (Though I'd say wait at least a couple weeks before doing > that!) > > On Wed, Sep 09, 2026 at 09:42:31AM +0300, Anastasios Papagiannis wrote: > > The NOMMU implementation of access_process_vm() rejects address ranges > > whose end wraps around, but access_remote_vm() bypasses this check even > > though both functions delegate to __access_remote_vm(). > > > > Move the wraparound check into __access_remote_vm() so it applies to > > both entry points. > > > > This is originally reported in [1]. > > > > [1] https://lore.kernel.org/bpf/4ef240a5bea36ff84df9589671367832860795159386a4c8fba546a0fa8b786f@mail.kernel.org/ > > Probably better to drop this big and make this a Link: tag. My scripts (after much recent LLM-driven fancification) made this change automatically! It became Closes: https://lore.kernel.org/bpf/4ef240a5bea36ff84df9589671367832860795159386a4c8fba546a0fa8b786f@mail.kernel.org/ [1] But scripts didn't figure out how to add a Reported-by: as well. > > > > Fixes: f55f199b7d76 ("NOMMU: implement access_remote_vm") > > Cc: stable I think? Well why. I see in [1] "causing memory disclosure or a bus fault". OK, we care about that. So the changelog should tell people this very important info and should explain the circumstances which can lead to the failure. > > Signed-off-by: Anastasios Papagiannis > > Seems reasonable to me! So: > > Reviewed-by: Lorenzo Stoakes (ARM) Cool.