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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260811-arch_numa-avoid-fortify-warning-v1-1-59ce3e689f3a@kernel.org> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/yXNQQrCMBBA0auUWTuQxBKLVxGRMZ20I5jIpK1K6 d2Nunyb/1corMIFjs0KyosUyanC7hoII6WBUfpqcMZ501mLpGG8pPlOSEuWHmPWSeIbn6RJ0oD eU+wOrdm31kGtPJSjvH6H0/nvMl9vHKZvFrbtA/ITFe6DAAAA X-Change-ID: 20260811-arch_numa-avoid-fortify-warning-66af87403412 To: Mike Rapoport , Andrew Morton Cc: Nick Desaulniers , Bill Wendling , Justin Stitt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, stable@vger.kernel.org, Nathan Chancellor X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=4393; i=nathan@kernel.org; h=from:subject:message-id; bh=SlLaVPw6ZHbuS1BVax13M+yBfy0AfsczeTQZub6iweA=; b=owGbwMvMwCUmm602sfCA1DTG02pJDFk1zJrOP7fuuht76JlD5PGGl59vHxWM9/h2mCXXaf1aQ YbvR7cUdJSyMIhxMciKKbJUP1Y9bmg45yzjjVOTYOawMoEMYeDiFICJ7F7C8IeXOzH4cFOKb9cR /zrj6XsiH7v37Enfkbrpm7Bh9PxT0dWMDPu7yrs4b747+PD6/TbFmRe2/t+zbKvj9i8rXiae3Bn 9bjUnAA== X-Developer-Key: i=nathan@kernel.org; a=openpgp; fpr=2437CB76E544CB6AB3D9DFD399739260CB6CB716 X-Rspam-User: X-Rspamd-Queue-Id: 0D277160003 X-Rspamd-Server: rspam07 X-Stat-Signature: hfdocqd8ajf5grjinb5qxisaz8sjh8wz X-HE-Tag: 1786512175-765324 X-HE-Meta: U2FsdGVkX1//51Ygh9j+SS6WYn7tkCHPjLUeTCSABHtkI/1Fe8tGbshzCIbanJWnZpmHEQN4/7tG1yVkl5U5obByPoT0bhsKSs3eRWh09eAXKH4pj3Z10roP3zckyrAhXXX9QYhzywrTuDV27Nc2ckAQZV6VMnQR8RgXUgBxIdqmpJrc5mwfes+q6XWIRFE2fo6uQG8nvfcCR7xhbmSQpeLlpXdlaL4kjqIaUg5Xlowt8jnua47sn4HHI495BFvy8xxR9k47S8WotQ1f3aoJLsGptIR7VLIJNCOaJGNVLdFZGaYQTE0+pu+N0JzgLqxdefU6qcdhxvzM61azc4r7dVyHSHDG7IyBW1FOn75SuuJPLyGYKbxRporbIp0xL9kNMl0qV1rXih3KIAAUpel2sp/ExD9zUjDwYn8EVolNWXln1KT3wrR6pt4MJHJHO6Ql6iJ9NIE9X7cz0S+t1y929ecYFW5Gzd9LaVH+tF9RzSxOFR3PpdkjE/bSuVhK5Ax+C2Vzcs+PJZvuJkk6BECrrlZUCA0eSDN+Wng1PADniABS9JQKp0cRvLZVjuo/+WU9MdzAQWPJbDtejk8j0+Z7HnXbyXM6qwxLIHz7WqnlYOIC7zwC8TWHWC1QKwma8rn8RKKFnZ2kjVOgpCvTIl6NtGcSzCxhr9LBIHgK4rEuvztdx14I0VtmOtnM4869/fd3O5fD7iCQ7/EOl+JGSTFFBG0yaFcJqzHIwXUdELlS7tT0DLAkBwoz1CsVRrkSb6SJq998S5WvgvnFmHGAUg2EGBa7zTpOxwgcJpEihdWv2jvn+3IclpDsYvhCMzxTFsNcl8SfH7DGeD9y7hkawZlhsc36Jn8n5zoSQCYTVPiBa3A6MeCRBrd43k+fy4d11EvfrRsf3RiMygSCGcENTMt0FHHc4UqmgHXvcSSejVFQp4LQGvP6tIIpdEg08gECfNAhMN5NN+ywwUzsiv+5AC2 B0rBZ6pg MA7Yl/9yTRfrpUorkORliCjyJBhDqw73y5XcHEvYtzmdUg/VHGWp5P2Brn8dyyUshJSR6574/qorryUgQ3bK1HB5RNoiQ6qO5eyG7eqzmsvFdHxWX2qjqzW/rgZKmEyzONWzV9Xr+oXswyO7E1oTAy/tqshXtwGxD5k95I/AeO25TG9ypVMsTQbwZxfO3L7TNf5XmpQd+342bw8YYtkBRGHomLUTSqk8XHk6fTC+o9U+rLirzJCPSKJlNWSOZHbkylNxBFAyTFydNgFXi2cGrrnG3UT2BfK5mFEgXQXOY/Y32A5fA5LJtR/uad2chGLSE++Fc Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When building ARCH=riscv using clang with CONFIG_FORTIFY_SOURCE and CONFIG_UBSAN_BOUNDS enabled, CONFIG_NR_CPUS > 64, and the default value of 2 for CONFIG_NODES_SHIFT, there is a compiletime warning from the fortify routines. In file included from mm/arch_numa.c:11: In file included from include/linux/acpi.h:14: In file included from include/linux/resource_ext.h:11: In file included from include/linux/slab.h:17: In file included from include/linux/gfp.h:7: In file included from include/linux/mmzone.h:8: In file included from include/linux/spinlock.h:60: In file included from include/linux/interrupt_rc.h:17: In file included from include/linux/smp.h:13: In file included from include/linux/cpumask.h:11: In file included from include/linux/bitmap.h:13: In file included from include/linux/string.h:383: include/linux/fortify-string.h:430:4: warning: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribue-warning] 430 | __write_overflow_field(p_size_field, size); | ^ include/linux/fortify-string.h:430:4: note: called by function 'fortify_memset_chk(unsigned long, unsigned long, unsigned long)' include/linux/bitmap.h:248:3: note: inlined by function 'setup_node_to_cpumask_map' 248 | memset(dst, 0, len); | ^ include/linux/fortify-string.h:462:25: note: expanded from macro 'memset' 462 | #define memset(p, c, s) __fortify_memset_chk(p, c, s, \ | ^ include/linux/fortify-string.h:453:2: note: expanded from macro '__fortify_memset_chk' 453 | fortify_memset_chk(__fortify_size, p_size, p_size_field), \ | ^ include/linux/fortify-string.h:430:4: note: use '-gline-directives-only' (implied by '-g1') or higher for more accurate inlining chain locations 430 | __write_overflow_field(p_size_field, size); | ^ 1 warning generated. In this configuration, MAX_NUMNODES is 4. clang unrolls the for loop in setup_node_to_cpumask_map() past this, which triggers the fortify check when accessing node_to_cpumask_map on the theoretical fifth loop iteration because it would be an out of bounds write. Make it clear to clang that nr_node_ids is bounded by MAX_NUMNODES due to the logic in setup_nr_node_ids() by early returning in setup_node_to_cpumask_map() should that condition be violated. Cc: stable@vger.kernel.org # all applicable Closes: https://github.com/ClangBuiltLinux/linux/issues/2174 Signed-off-by: Nathan Chancellor --- This is based on mm-unstable due to the move of arch_numa.c from mm/ to drivers/base/ living there. I have CC'd stable because this warning appears in my testing back to at least 6.1 but I see no reason why it should not apply to all trees. No fixes tag since this is a layered problem that just happens to appear under certain conditions. Another alternative would be using the __assume macro to say something like __assume(nr_node_ids <= MAX_NUMNODES); but that seems a little more fragile. --- mm/arch_numa.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/mm/arch_numa.c b/mm/arch_numa.c index 442ea239bba7..bd7772b05bcf 100644 --- a/mm/arch_numa.c +++ b/mm/arch_numa.c @@ -105,6 +105,18 @@ static void __init setup_node_to_cpumask_map(void) if (nr_node_ids == MAX_NUMNODES) setup_nr_node_ids(); + /* + * This check should never be true but it makes it clear to compilers + * that node_to_cpumask_map is bound by nr_node_ids, avoiding false + * positive fortify warnings when accessing node_to_cpumask_map in the + * for loop below. + */ + if (unlikely(nr_node_ids > MAX_NUMNODES)) { + pr_err("nr_node_ids (%u) is larger than MAX_NUMNODES (%d)", + nr_node_ids, MAX_NUMNODES); + return; + } + /* allocate and clear the mapping */ for (node = 0; node < nr_node_ids; node++) { alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]); --- base-commit: 47870fb9b0e3bd20b45e3a069b4c766f3dcb721a change-id: 20260811-arch_numa-avoid-fortify-warning-66af87403412 Best regards, -- Cheers, Nathan