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[209.85.208.182]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-2f3b7703492sm15802381fa.91.2024.08.19.12.33.34 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Aug 2024 12:33:35 -0700 (PDT) Received: by mail-lj1-f182.google.com with SMTP id 38308e7fff4ca-2ef2d96164aso55130281fa.3 for ; Mon, 19 Aug 2024 12:33:34 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCWFIjJKT8OKCEJ7A9NzIXjQh+BFmL9gcPwHAbHxr0Zg87/OvTkDOmHrwUaKWOpvTfKSxCxUFO+PhJKnMEh0OZpF8Rg= X-Received: by 2002:a2e:9595:0:b0:2ec:55b5:ed45 with SMTP id 38308e7fff4ca-2f3be5978f6mr76523451fa.24.1724096014503; Mon, 19 Aug 2024 12:33:34 -0700 (PDT) MIME-Version: 1.0 References: <20240817062449.21164-1-21cnbao@gmail.com> <7050deab-e99c-4c83-b7b9-b5dad42f4e95@redhat.com> In-Reply-To: From: Linus Torvalds Date: Mon, 19 Aug 2024 12:33:17 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 0/4] mm: clarify nofail memory allocation To: Barry Song <21cnbao@gmail.com> Cc: David Hildenbrand , akpm@linux-foundation.org, linux-mm@kvack.org, 42.hyeyoo@gmail.com, cl@linux.com, hailong.liu@oppo.com, hch@infradead.org, iamjoonsoo.kim@lge.com, mhocko@suse.com, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, urezki@gmail.com, v-songbaohua@oppo.com, vbabka@suse.cz, virtualization@lists.linux.dev Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 01A55100022 X-Stat-Signature: ur9xg8hxjyzr9dfumut17p6tg9uzbawe X-HE-Tag: 1724096017-459048 X-HE-Meta: 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 MsEt0JgK 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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: List-Subscribe: List-Unsubscribe: On Mon, 19 Aug 2024 at 12:23, Barry Song <21cnbao@gmail.com> wrote: > > > That could be an exploit taking advantage of those improper callers, So? FIX THE BUGGY CODE. Don't make insane and incorrect changes to the MM code and spread Fear, Uncertainty and Doubt. > thus it wouldn=E2=80=99t necessarily result in an immediate oops in calle= rs but > result in an exploit No. Any bug can be an exploit. Don't try to make this something special by calling it an exploit. NULL pointer dereferences are some of the *least* worrisome bugs, because we don't allow people to mmap the NULL area anyway. So just stop spreading FUD. We don't improve the kernel by making excuses for bugs, we improve it by fixing things. And any caller that asks for NOFAIL with bad parameters is buggy. The MM code should NOT try to fix it up, and dammit, BUG_ON() is not acceptable as a debugging help. Never was, never will be. Worry-warts already do "reboot-on-warn". Linus