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From: Kees Cook <kees@kernel.org>
To: Tiffany Yang <ynaffit@google.com>
Cc: "Nathan Lynch" <nathanl@linux.ibm.com>,
	"Steven Rostedt (Google)" <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org, kernel-team@android.com,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Arve Hjønnevåg" <arve@android.com>,
	"Todd Kjos" <tkjos@android.com>,
	"Martijn Coenen" <maco@android.com>,
	"Joel Fernandes" <joelagnelf@nvidia.com>,
	"Christian Brauner" <brauner@kernel.org>,
	"Carlos Llamas" <cmllamas@google.com>,
	"Suren Baghdasaryan" <surenb@google.com>,
	"Brendan Higgins" <brendan.higgins@linux.dev>,
	"David Gow" <davidgow@google.com>, "Rae Moar" <rmoar@google.com>,
	linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com
Subject: Re: [PATCH v4 6/6] binder: encapsulate individual alloc test cases
Date: Thu, 17 Jul 2025 00:34:52 -0700	[thread overview]
Message-ID: <202507170026.0850E08ED@keescook> (raw)
In-Reply-To: <202507162326.5A827E93C@keescook>

On Wed, Jul 16, 2025 at 11:32:10PM -0700, Kees Cook wrote:
> This really screams for a struct-based way to in-place declare a
> seq_buf. The current macro only works on the stack. I think this
> will work; I'll send a patch once I get it tested:
> 
> #define DECLARE_SEQ_BUF(NAME, SIZE)		\
> 	char NAME##_buffer[size];		\
> 	struct seq_buf NAME = {			\
> 		.buffer = &NAME##_buffer,	\
> 		.size = SIZE,			\
> 	}

Oh, no, that wouldn't work in a struct -- there is a static initializer
there. And my memory is short: this would have been a revert of commit
7a8e9cdf9405 ("seq_buf: Make DECLARE_SEQ_BUF() usable").

I don't think it's possible to construct a seq_buf in a struct without a
runtime initialization. And that's true for anything that needs to
actually set a value (size) for the data type to be usable. Hmpf.

-- 
Kees Cook

  reply	other threads:[~2025-07-17  7:34 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-17  1:10 [PATCH v4 0/6] binder: Set up KUnit tests for alloc Tiffany Yang
2025-07-17  1:10 ` [PATCH v4 1/6] binder: Fix selftest page indexing Tiffany Yang
2025-07-17  6:23   ` Kees Cook
2025-07-17  1:10 ` [PATCH v4 2/6] binder: Store lru freelist in binder_alloc Tiffany Yang
2025-07-17  6:23   ` Kees Cook
2025-07-17  1:10 ` [PATCH v4 3/6] kunit: test: Export kunit_attach_mm() Tiffany Yang
2025-07-17  1:10 ` [PATCH v4 4/6] binder: Scaffolding for binder_alloc KUnit tests Tiffany Yang
2025-07-17  1:10 ` [PATCH v4 5/6] binder: Convert binder_alloc selftests to KUnit Tiffany Yang
2025-07-17  6:33   ` Kees Cook
2025-07-17  1:10 ` [PATCH v4 6/6] binder: encapsulate individual alloc test cases Tiffany Yang
2025-07-17  6:32   ` Kees Cook
2025-07-17  7:34     ` Kees Cook [this message]
2025-07-17 14:41 ` [PATCH v4 0/6] binder: Set up KUnit tests for alloc Greg Kroah-Hartman
2025-07-21 16:22 ` Joel Fernandes

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