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AJvYcCXPZnxJ8TTPgYnE003cgEh5W6jusGtxZdvj3TgBeDtdah3Z+Jk/EVm+2l05zi98V9Y/VMefoJhC1e06KVMJ4CKSQbM= X-Gm-Message-State: AOJu0Yw9IvSeFYM7JiuS0BwpVLV7p1XRoInqk4O6reaZh6N/bxSqdKA6 baBo3GolNrPVAjUkPnqRP68xtC93hzsy0fBjPrhm+yNmtE+HSB97uSuJqVunBfZtpOi+yzbXItz RjY7GlRaVeIfOSzIJA9/FpoV47hI= X-Google-Smtp-Source: AGHT+IFGWC8hsGOqXtm4aiyNN9e/zdL0TbBTDi/OQqi7gWzwfHy+sZTqJrtxtSLVBk9rsSortx6XkZUJkL1RJDoW7mU= X-Received: by 2002:a05:6102:338b:b0:48f:eb5f:84d8 with SMTP id ada2fe7eead31-49159a20297mr3374292137.27.1721288505756; Thu, 18 Jul 2024 00:41:45 -0700 (PDT) MIME-Version: 1.0 References: <20240717230025.77361-1-21cnbao@gmail.com> In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Thu, 18 Jul 2024 19:41:33 +1200 Message-ID: Subject: Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL To: Michal Hocko Cc: akpm@linux-foundation.org, linux-mm@kvack.org, Barry Song , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: B857F14000A X-Stat-Signature: t94yp5rewgepnmr8nhspgs3fguobqs4c X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1721288506-910163 X-HE-Meta: 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 aaX3TzeA 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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 Thu, Jul 18, 2024 at 7:27=E2=80=AFPM Michal Hocko wrot= e: > > On Thu 18-07-24 19:22:37, Barry Song wrote: > [...] > > For future-proofing and security reasons, returning NULL for NOFAIL > > still seems incorrect as the callers won't check the ret. If any future= or > > existing in-tree code has a potential bug which might be exploited by > > hackers, for example > > > > ptr =3D kvmalloc_array(NOFAIL); > > ptr->callback(); //ptr=3DNULL; > > > > callback could be a privilege escalation? > > Only if you allow to map zero page AFAIK. Nobody reasonable should be > doing that. ptr->callback could be above /proc/sys/vm/mmap_min_addr ? > > -- > Michal Hocko > SUSE Labs