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[209.85.208.173]) by smtp.gmail.com with ESMTPSA id q26sm2528958lfm.53.2021.04.07.09.07.34 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 07 Apr 2021 09:07:34 -0700 (PDT) Received: by mail-lj1-f173.google.com with SMTP id 15so21399567ljj.0 for ; Wed, 07 Apr 2021 09:07:33 -0700 (PDT) X-Received: by 2002:a2e:9bd0:: with SMTP id w16mr2540948ljj.465.1617811653798; Wed, 07 Apr 2021 09:07:33 -0700 (PDT) MIME-Version: 1.0 References: <20210401181741.168763-1-surenb@google.com> In-Reply-To: From: Linus Torvalds Date: Wed, 7 Apr 2021 09:07:17 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 0/5] 4.14 backports of fixes for "CoW after fork() issue" To: Vlastimil Babka Cc: Suren Baghdasaryan , Peter Xu , stable , Greg Kroah-Hartman , Jann Horn , Kirill Tkhai , Shaohua Li , Nadav Amit , Linux-MM , Linux Kernel Mailing List , Android Kernel Team , Andrea Arcangeli , David Hildenbrand , Jason Gunthorpe Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 00E6340002DB X-Stat-Signature: 67zjizotiaq8nutdcrju1hsz91dw5ysn Received-SPF: none (linuxfoundation.org>: No applicable sender policy available) receiver=imf10; identity=mailfrom; envelope-from=""; helo=mail-lf1-f52.google.com; client-ip=209.85.167.52 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617811653-596261 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 Wed, Apr 7, 2021 at 6:22 AM Vlastimil Babka wrote: > > 1) Ignore the issue (outside of Android at least). The security model of zygote > is unusual. Where else a parent of fork() doesn't trust the child, which is the > same binary? Agreed. I think this is basically an android-only issue (with _possibly_ some impact on crazy "pin-and-fork" loads), and doesn't necessarily merit a backport at all. If Android people insist on using very old kernels, knowing that they do things that are questionable with those old kernels, at some point it's just _their_ problem. Linus