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b=ZEhQN4GAOPhASTFcl0yG0oHUXqD+yfoiSdvt6qFToohSp1gkqe+tnbg5iw2UDNT95 ZcTR0q54BV1+jxFdsZZbUjWnn6U7ji9okb8mXoNvwK1G4FHK6hQ3k8TMhP4a7c1jhS T+e/RyqP6dtNMTzhASmm0jZBz9+BngBBa3qdzeQW5INRn1QDAfgFXHuI56ZuXWYFu+ /3c3SUnBXjfc7jtPGEZJXVUDq+x5sgBZtJlkw0WCJy5ERckiqON21t+2sryUSijJ0Z b4xZyZ7B9Kx2+O9uc9/wK/umZA42u1V33/nhxuZzRCy0vTcIulghVKUP/wPvt0/OCJ j/UQ3LmDVli5Q== Date: Fri, 25 Sep 2026 14:08:58 +0100 From: "Lorenzo Stoakes (ARM)" To: Hajime Tazaki Cc: akpm@linux-foundation.org, tasos.papagiannnis@gmail.com, 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: References: <20260909064231.18693-1-tasos.papagiannnis@gmail.com> <20260909001341.6a7c3556259f7cf9a79c1da7@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 100D2160006 X-Rspam-User: X-Stat-Signature: c6qkt5sj6f1rarxury6thdqam6ts6hhd X-HE-Tag: 1790341745-231263 X-HE-Meta: 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 jtQLzvsO r/1guMKAEaW6RrEWr2dbseZXhpBEHKm/MdYNSax4tI3FWW12FJFj8ebGgtr35+RnONljYvf7gjMOgpZgYuXDo791wwf0cf3TAZzN+itokgWqcUIaDTf/f48Rm8wL3HzloOf94v/TIjHoCbS7EDZM8OUkN70QVOgslPG7StbyIWzl7cyCXSrS87v4jHebXQCZOaxMWUR4Ijh0+YqsFS4UacououMknKg1OSeEoJoy5LSHtCGy7YAiMqV2yxnggUsOcxNLRTkamdAxasY26/GlfcEL1Dh2U+4+D7MgzAz8ZACZRkx7GoPGLrzy7G+IOZf01Kn8IVH/wvdJh76VnyZawX+sJ5/FHKduQZOEjLVEIobO0eSkxqniP8CCinifsGRzqVKndS5XK0Afq82aYxPMl2WWECtsCr8QQlN4cIxnXDLp0Ms15binsIpdOUVYYTXTvcP3BbZtHe3qknbOcNDVC/M9dmiZYDkSoVuY0 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Sep 10, 2026 at 05:11:03AM +0900, Hajime Tazaki wrote: > > Hello, > > On Wed, 09 Sep 2026 16:13:41 +0900, > Andrew Morton wrote: > > > > On Wed, 9 Sep 2026 09:42:31 +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. > > > > lgtm, thanks. > > > > > This is originally reported in [1]. > > > > > > [1] https://lore.kernel.org/bpf/4ef240a5bea36ff84df9589671367832860795159386a4c8fba546a0fa8b786f@mail.kernel.org/ > > > > Ah, bpfbot scored one. > > > > Sashiko might have found more issues in there: > > https://sashiko.dev/#/patchset/20260909064231.18693-1-tasos.papagiannnis@gmail.com > > > > I'll optimistically cc Hajime Tazaki, who has been doing some NOMMU > > work recently. > > I got a similar review (from Sashiko) that current use of > !vma->vm_file isn't appropriate and should use vma_set_anonymous(). IIUC > that case happens only (I may miss something) with /dev/zero (via > mmap_zero_prepare()). That's no longer an issue as MAP_PRIVATE-/dev/zero is truly anon now. > > I also had a patch but am currently waiting for Lorenzo's input for > his work on /dev/zero, which mentioned in his reply. Sorry, I just added a script to find call outs in neomutt :) As above. > > https://lore.kernel.org/linux-mm/an8BlTgk7sc5vFJ1@lucifer/ > > Thus 3 comments of Sashiko (all about vma->vm_file) can be addressed > in future, and are not needed an immediate fix. You can use vma_is_anonymous() now. > > I wish to ask this to Lorenzo too. > > -- Hajime -- Cheers, Lorenzo