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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id s6-20020a5d6a86000000b003142ea7a661sm1772109wru.21.2023.07.27.04.15.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 Jul 2023 04:15:28 -0700 (PDT) Message-ID: Date: Thu, 27 Jul 2023 13:15:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v1] mm: Fix use-after-free for MMU_GATHER_NO_GATHER To: Ryan Roberts , Andrew Morton , Matthew Wilcox , Yin Fengwei , Yu Zhao , Yang Shi , "Huang, Ying" , Zi Yan , Nathan Chancellor Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20230727110224.3333682-1-ryan.roberts@arm.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230727110224.3333682-1-ryan.roberts@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 57D51140015 X-Rspam-User: X-Stat-Signature: jt98hhyggjz6j95zxxkifq5b753egoip X-Rspamd-Server: rspam03 X-HE-Tag: 1690456532-337959 X-HE-Meta: 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 hBaCvjmo 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 27.07.23 13:02, Ryan Roberts wrote: > The recent change to batch-zap anonymous ptes did not take into account > that for platforms where MMU_GATHER_NO_GATHER is enabled (e.g. s390), > __tlb_remove_page() drops a reference to the page. This means that the > folio reference count can drop to zero while still in use (i.e. before > folio_remove_rmap_range() is called). This does not happen on other > platforms because the actual page freeing is deferred. > > Solve this by appropriately getting/putting the folio to guarrantee it > does not get freed early. > > Given the new need to get/put the folio in the batch path, let's stick > to the non-batched path if the folio is not large. In this case batching > is not helpful since the batch size is 1. > > Signed-off-by: Ryan Roberts > Fixes: 904d9713b3b0 ("mm: batch-zap large anonymous folio PTE mappings") > Reported-by: Nathan Chancellor > Link: https://lore.kernel.org/linux-mm/20230726161942.GA1123863@dev-arch.thelio-3990X/ > --- > > Hi Andrew, > > This fixes patch 3 in the series at [1], which is currently in mm-unstable. I'm > not sure whether you want to take the fix or whether I should re-post the entire > series? > Please repost the complete thing, you're touching some sensible places that really need decent review. -- Cheers, David / dhildenb