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AJvYcCUgBu0m9klR0YoP3U+EFNASR5VK0YL1I8RNISKEaabage2GHOatM/fdXwKNyfQ3Dlw3EADV5zVMaOk=@vger.kernel.org, AJvYcCXvrjFtAFYHGum5FHJASTrqb/C8te+ql+AnnFB9ldblN8YXwnylqgcwMrvXVR1D+IDJQeA1t+a4EuYxXVF0@vger.kernel.org X-Gm-Message-State: AOJu0YxcDFCxySDze4b38AVcJKQGhhoj60NaYrg3MmMLHeAPa84lH3/f /a181ejhzPFEVqxEMlHplDl8auGXHYXJ5pGeWwdnLhgqXsUoTbwhflS8rAU9ND2VbJXabHnv/Ov Vp9vHh8jbXbYC5vPxTNc3GhGFS90= X-Gm-Gg: ASbGnctWM3lVKCUr/lusW9igleYpUGthJS+apqqHOmWDsI+3a7o7t+t6IB0c7sJZ/p3 3OQseMX10ZIuNh/H+A7fyI3fOVbgOtGaOsPdcptS3ZGR9ZSXmU2OyMsEmGN3Xo1PU4MIxuObNx4 GHw3GUSKD2a2wpOidkiNqXexn+jmY= X-Google-Smtp-Source: AGHT+IFUQsaiMRIvtR5jHluzCMQLuQzpGcI8hgAnBbkdkQFmyrZjRH1+Z3aerVqSjjiLZTXQuXJjMTVOJy208Ija/YY= X-Received: by 2002:a05:6000:1447:b0:391:3207:2e75 with SMTP id ffacd0b85a97d-3996b45f0d3mr4021787f8f.18.1742311978657; Tue, 18 Mar 2025 08:32:58 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <168f775c4587f3a1338271390204a9fe16b150dd.1739866028.git.maciej.wieczor-retman@intel.com> In-Reply-To: From: Andrey Konovalov Date: Tue, 18 Mar 2025 16:32:46 +0100 X-Gm-Features: AQ5f1JrJPlldmh-W4saMlKXW0Ok9D48DqwKxa7GZ64X93-bATE_KAdVxzbhhhSM Message-ID: Subject: Re: [PATCH v2 01/14] kasan: sw_tags: Use arithmetic shift for shadow computation To: Maciej Wieczor-Retman Cc: kees@kernel.org, julian.stecklina@cyberus-technology.de, kevinloughlin@google.com, peterz@infradead.org, tglx@linutronix.de, justinstitt@google.com, catalin.marinas@arm.com, wangkefeng.wang@huawei.com, bhe@redhat.com, ryabinin.a.a@gmail.com, kirill.shutemov@linux.intel.com, will@kernel.org, ardb@kernel.org, jason.andryuk@amd.com, dave.hansen@linux.intel.com, pasha.tatashin@soleen.com, guoweikang.kernel@gmail.com, dwmw@amazon.co.uk, mark.rutland@arm.com, broonie@kernel.org, apopple@nvidia.com, bp@alien8.de, rppt@kernel.org, kaleshsingh@google.com, richard.weiyang@gmail.com, luto@kernel.org, glider@google.com, pankaj.gupta@amd.com, pawan.kumar.gupta@linux.intel.com, kuan-ying.lee@canonical.com, tony.luck@intel.com, tj@kernel.org, jgross@suse.com, dvyukov@google.com, baohua@kernel.org, samuel.holland@sifive.com, dennis@kernel.org, akpm@linux-foundation.org, thomas.weissschuh@linutronix.de, surenb@google.com, kbingham@kernel.org, ankita@nvidia.com, nathan@kernel.org, ziy@nvidia.com, xin@zytor.com, rafael.j.wysocki@intel.com, andriy.shevchenko@linux.intel.com, cl@linux.com, jhubbard@nvidia.com, hpa@zytor.com, scott@os.amperecomputing.com, david@redhat.com, jan.kiszka@siemens.com, vincenzo.frascino@arm.com, corbet@lwn.net, maz@kernel.org, mingo@redhat.com, arnd@arndb.de, ytcoode@gmail.com, xur@google.com, morbo@google.com, thiago.bauermann@linaro.org, linux-doc@vger.kernel.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Mar 14, 2025 at 4:58=E2=80=AFPM Maciej Wieczor-Retman wrote: > > >KASAN does nothing to deliberately prevent or detect races. Even if > >the race leads to an OOB or UAF, KASAN might not be able to detect it. > >But sometimes it does: if poisoned shadow memory values become visible > >to the other thread/CPU before it makes a shadow memory value check. > > Thanks :) > > I've came up with a theoretical issue for the following dense series that= might > happen if there is some racing but I'll have to experiment if it actually > happens. As long as it doesn't lead to false positive reports or crashes in the KASAN runtime - I think it should fine.