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Silva" , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, thomas.weissschuh@linutronix.de Subject: Re: [PATCH] kasan: add KUnit tests for __counted_by and __counted_by_ptr Message-Id: <20260928164235.041803152d3f340d4c59e59e@linux-foundation.org> In-Reply-To: <20260928231737.2092716-1-morbo@google.com> References: <20260928231737.2092716-1-morbo@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 90CCD4000B X-Rspam-User: X-Stat-Signature: b1soixtznfnf47urc3orxdfq6kbdqmw4 X-HE-Tag: 1790638957-540995 X-HE-Meta: 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 vgKSbc9V BHRvR654NgKY3MHV/qjQiZOgyNLjpsRh3CsSu6G/hOE2JzN1mVh/E78JwooWW2fig40Wji1FKsfRKp6O9E5E5mGK1pFb+pfWdeQoJiuS/ttVNzpjx0wWE4fcco6mN6oG6d82d3uhpfd3hPJpIrD/QL8FDSOof/D1jGSxQBiTsntCElOK0t43Nf1J8YufDB6O3YAdx05p3riYA+Uj5ONlGUGDW8WD2ROCkHme3ATVFhTnV1vO7TnfrbPBNJdyxM786LUMNpj8pFVXQm/vpt/+YoR/Rlvi+97hBVRoE6mX9azneim5L6wdpUoEVJWNwyi/du1h1tFk7zHHYyGXIbeS0loNlr6KelA6ek1TjHUp/CQ3mTAZ4CzL/p0mZfUNnUzqO/dZ1zWTYJ+RjHF+jt2vgN5yRxP1SpEaum755Ch+wKmpsDDZjmCIzSIIegZ6y58daD5QD4I6u9E+aCVs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 28 Sep 2026 23:17:37 +0000 Bill Wendling wrote: > The '__counted_by' and '__counted_by_ptr' attributes associate a > flexible array member or pointer member with a struct field that holds > its element count. Supporting compilers use these annotations to > compute dynamic object sizes via '__builtin_dynamic_object_size()' and > perform runtime bounds checking with KASAN. > > Add KUnit tests ('counted_by_flex_oob_access' and > 'counted_by_ptr_oob_access', guarded by CONFIG_CC_HAS_COUNTED_BY and > CONFIG_CC_HAS_COUNTED_BY_PTR respectively) to verify that: > > - '__builtin_dynamic_object_size()' returns the expected byte size for > annotated flexible array and pointer members. > - KASAN detects out-of-bounds read and write accesses beyond the > annotated count. > > Allocate the test structures in 'noinline' helpers and hide the > returned pointers with OPTIMIZER_HIDE_VAR() so allocation-size > attributes and compiler optimizations do not mask the '__counted_by' > and '__counted_by_ptr' checks. Thanks. Are any of Sashiko's comments pertinent? https://sashiko.dev/#/patchset/20260928231737.2092716-1-morbo@google.com