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AJvYcCVGOTnIMFIDt+OkWAjIX6hFiZi6Or2kOibfkWIcVai3xq8xUcDvvj9U1+BkrFORCesS3YoypFvkzSMSllmcBry5DFM= X-Gm-Message-State: AOJu0YwmB+35yc9Wzn7ACtcWlSmGncAwFZv3ngPWQtCf8FPD+3A4jFKP nS46rk2GJVET4+SUSypWjsbTpFsG75WV94ZuwUf40mz4z43QxZcyGXqVphPtOzfRpQ9u8fWahMm 4SPH1iTS+jhZhbu6aTDMW7ybmlHCy1KPIOdWc X-Google-Smtp-Source: AGHT+IFIduuZE1STvNicF9DxUXXadRzIx8lN/0f7DXD7a7IgTSoghi+1HrvGMrI5m8lZfvX3Zk7o2MADsuuEWWIky8I= X-Received: by 2002:a25:ac68:0:b0:dc6:d158:98f0 with SMTP id r40-20020a25ac68000000b00dc6d15898f0mr6974706ybd.52.1707783323411; Mon, 12 Feb 2024 16:15:23 -0800 (PST) MIME-Version: 1.0 References: <20240212213922.783301-1-surenb@google.com> <20240212213922.783301-34-surenb@google.com> <202402121445.B6EDB95@keescook> In-Reply-To: <202402121445.B6EDB95@keescook> From: Suren Baghdasaryan Date: Mon, 12 Feb 2024 16:15:12 -0800 Message-ID: Subject: Re: [PATCH v3 33/35] codetag: debug: mark codetags for reserved pages as empty To: Kees Cook Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, corbet@lwn.net, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, dennis@kernel.org, tj@kernel.org, muchun.song@linux.dev, rppt@kernel.org, paulmck@kernel.org, pasha.tatashin@soleen.com, yosryahmed@google.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, andreyknvl@gmail.com, ndesaulniers@google.com, vvvvvv@google.com, gregkh@linuxfoundation.org, ebiggers@google.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, cgroups@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: ABA1720010 X-Stat-Signature: 7y7eqok9a3wyd7gjshcd1q9mzncpwqsr X-Rspam-User: X-HE-Tag: 1707783324-272342 X-HE-Meta: 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 mIHsrrqN Vn4Mz64MNDol0zSRb6jY4tL2aHUcP548x7B4ZvjmgKv+H08eu5QV0lrWFB8bRYAA+qbAdc79hON/a9/q0+EbNmzBUIWMPUnig52KSAbYlUvfw19UyjwKYHK9O8YA9bFWoxApceP/m4UbFPOIihIp+ImSsgZQY1/6Dx/4xfnsi6pl0QKQYza0Ftpxi+EbcwP95cnjvC5+F7W9mEv8wHczYyiHYu3n4CbG7MoLW+XXlWaLP/XeA8YfhpW/rUE6yPchQcSe0S7SlqpFMMZl1iggddCJ82pLXBunOsXKmvyM00jsLDuWZxhlMg/62pUVI9+TEzF0TcylAGfnuKNEgeME4FFKyVW+h3/3e3JQ1pdn60Z6iiIY05CoOrk5FojAOc+2vMSV7 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, Feb 12, 2024 at 2:45=E2=80=AFPM Kees Cook w= rote: > > On Mon, Feb 12, 2024 at 01:39:19PM -0800, Suren Baghdasaryan wrote: > > To avoid debug warnings while freeing reserved pages which were not > > allocated with usual allocators, mark their codetags as empty before > > freeing. > > How do these get their codetags to begin with? The space for the codetag reference is inside the page_ext and that reference is set to NULL. So, unless we set the reference as empty (set it to CODETAG_EMPTY), the free routine will detect that we are freeing an allocation that has never been accounted for and will issue a warning. To prevent this warning we use this CODETAG_EMPTY to denote that this codetag reference is expected to be empty because it was not allocated in a usual way. > Regardless: > > Reviewed-by: Kees Cook > > -- > Kees Cook