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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a568a72cd3sm7231201f8f.32.2025.06.15.01.11.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Jun 2025 01:11:43 -0700 (PDT) Date: Sun, 15 Jun 2025 09:11:42 +0100 From: David Laight To: kernel test robot Cc: Ilya Leoshkevich , oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org, Andrew Morton , Linux Memory Management List , Alexander Potapenko Subject: Re: mm/kmsan/hooks.c:269:14: sparse: sparse: cast removes address space '__user' of expression Message-ID: <20250615091142.3c9520d9@pumpkin> In-Reply-To: <202506131242.qB8fUSlP-lkp@intel.com> References: <202506131242.qB8fUSlP-lkp@intel.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: A6E7DC000D X-Stat-Signature: j8crw5w4ntn7ryu9naytabhxxo1876yo X-Rspamd-Server: rspam04 X-HE-Tag: 1749975105-704592 X-HE-Meta: U2FsdGVkX19iqXkqQpdPgP3N8cmaNFrALPWN9RA8MXiVm75Mh8CPivvX2MXG/7br9VauEQWwKZX7jgFXbom+cAzgtzpbbCOKP1mx9UAHOUb5tGL37cde9ErFtp8zuF0ZCldp9YFT12OgCugibu7ayc/cxtwWlc1izUiN2QZWbpuNYk1Pj33+RYg7Ovo1H6nnU6dG3FNyv5V8RhDMFi/bv1LTqXeljwjiyMjOawDHm8FtXcVldXdRcnE9f4cLduWiuGBzvaLEdkcc59qk9vuj/JIxgeNApOwxBrXdWWEhQ1VAKt+Aa/LW2ylU8foCGfa/fSgqUhfrDKphPIIxWvBAHIugJLpBOapx0Y/W/2egDihhLyURl1LUGPp+i4BrtaHXhlZ1ULiGqRbtWmGIyDaHel/BxGcf9BLLbO/t9nOnAHWjroy2falFUPgn49hFgmDGVvIHJl91gi3/2W+ASxRKMabMP408L2soI07VZHJZinIZOjeCyW9RI9FVM1S1Ewtzhlm1vbQQEKPWtaRY9eEMgdRvhhuU5q286LiFMfpjct/mXsGPPTAZ5SPcbtCbQviNLvO8gzr7tfmZxcOOu8WikQMabOGkMsLM4Fydurlaq1sHvdgFGjK+elvA32WmhAkTj9y+3FDvzwNV+aG9tkJLkZT4zhzUPQIhCgaGo8Yado+d7PmWSEtR1+nhCwqF5c2Tzfj9CqfhDHLJxLy2BFZw+34DAZJ4bWIhJPwmU8AxzP3RVq+px1692Dxh2ZofSdZWQJmXzo/D/lk8TTAaEfCpAsM7FVfk0yB+F0z0xvL0asz80Ktt3IL8IkKNOOTwH2BahcgM1/AFXQigw9MnvR0ZSdz2NhSYTGqJGlGQt6ZgB5iNIgZqtgB/tl4LqtcguX/oIUnsR/JD+VHty5G7hb7/8XQYypLjfIe7QCbbO5UUAaT6+xBN8vMC4OTq/nFEbSm51UiUwQ6I8lPxc7mEJ6x cTSvoVIc 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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 Fri, 13 Jun 2025 12:28:55 +0800 Not directly related but... .... > 75cf0290271bf6 Alexander Potapenko 2022-09-15 267 ua_flags = user_access_save(); > f926e9326f3a79 Ilya Leoshkevich 2024-06-21 268 if (!IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) || > f926e9326f3a79 Ilya Leoshkevich 2024-06-21 @269 (u64)to < TASK_SIZE) { > 75cf0290271bf6 Alexander Potapenko 2022-09-15 270 /* This is a user memory access, check it. */ > 75cf0290271bf6 Alexander Potapenko 2022-09-15 271 kmsan_internal_check_memory((void *)from, to_copy - left, to, > 75cf0290271bf6 Alexander Potapenko 2022-09-15 272 REASON_COPY_TO_USER); > 75cf0290271bf6 Alexander Potapenko 2022-09-15 273 } else { > 75cf0290271bf6 Alexander Potapenko 2022-09-15 274 /* Otherwise this is a kernel memory access. This happens when a > 75cf0290271bf6 Alexander Potapenko 2022-09-15 275 * compat syscall passes an argument allocated on the kernel > 75cf0290271bf6 Alexander Potapenko 2022-09-15 276 * stack to a real syscall. > 75cf0290271bf6 Alexander Potapenko 2022-09-15 277 * Don't check anything, just copy the shadow of the copied > 75cf0290271bf6 Alexander Potapenko 2022-09-15 278 * bytes. > 75cf0290271bf6 Alexander Potapenko 2022-09-15 279 */ Isn't that comment just wrong? Compat syscalls just don't do that any more. They might have done it in the past before setfs(KERNEL_DS) got nuked. So the 'else' clause can never happen and the test nuked. So anything here is always 'user' (or will have failed access_ok()). I think that also means the test can be done before the copy_to_user() itself since, contrary to the earlier comment (trimmed) all of the kernel memory that might be copied needs to have valid data. (Unlike copy_from_user() when only the written part need to be marked as containing valid data.) David > 75cf0290271bf6 Alexander Potapenko 2022-09-15 280 kmsan_internal_memmove_metadata((void *)to, (void *)from, > 75cf0290271bf6 Alexander Potapenko 2022-09-15 281 to_copy - left); > 75cf0290271bf6 Alexander Potapenko 2022-09-15 282 } > 75cf0290271bf6 Alexander Potapenko 2022-09-15 283 user_access_restore(ua_flags); > 75cf0290271bf6 Alexander Potapenko 2022-09-15 284 } > 75cf0290271bf6 Alexander Potapenko 2022-09-15 285 EXPORT_SYMBOL(kmsan_copy_to_user); > 75cf0290271bf6 Alexander Potapenko 2022-09-15 286 > > :::::: The code at line 269 was first introduced by commit > :::::: f926e9326f3a79f7e01ac790e2361f44d8ca8320 kmsan: fix kmsan_copy_to_user() on arches with overlapping address spaces > > :::::: TO: Ilya Leoshkevich > :::::: CC: Andrew Morton >