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From: Florian Weimer <fweimer@redhat.com>
To: Aleksa Sarai <cyphar@cyphar.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>,  Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>,  Jan Kara <jack@suse.cz>,
	Arnd Bergmann <arnd@arndb.de>,  Shuah Khan <shuah@kernel.org>,
	Kees Cook <kees@kernel.org>,  Mark Rutland <mark.rutland@arm.com>,
	linux-kernel@vger.kernel.org,  linux-api@vger.kernel.org,
	linux-fsdevel@vger.kernel.org,  linux-arch@vger.kernel.org,
	linux-kselftest@vger.kernel.org, libc-alpha@sourceware.org
Subject: Re: [PATCH RFC v3 02/10] sched_getattr: port to copy_struct_to_user
Date: Tue, 10 Dec 2024 19:14:07 +0100	[thread overview]
Message-ID: <87y10nz9qo.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20241010-extensible-structs-check_fields-v3-2-d2833dfe6edd@cyphar.com> (Aleksa Sarai's message of "Thu, 10 Oct 2024 07:40:35 +1100")

* Aleksa Sarai:

> sched_getattr(2) doesn't care about trailing non-zero bytes in the
> (ksize > usize) case, so just use copy_struct_to_user() without checking
> ignored_trailing.

I think this is what causes glibc's misc/tst-sched_setattr test to fail
on recent kernels.  The previous non-modifying behavior was documented
in the manual page:

       If the caller-provided attr buffer is larger than the kernel's
       sched_attr structure, the additional bytes in the user-space
       structure are not touched.

I can just drop this part of the test if the kernel deems both behaviors
valid.

Thanks,
Florian


  reply	other threads:[~2024-12-10 18:14 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-09 20:40 [PATCH RFC v3 00/10] extensible syscalls: CHECK_FIELDS to allow for easier feature detection Aleksa Sarai
2024-10-09 20:40 ` [PATCH RFC v3 01/10] uaccess: add copy_struct_to_user helper Aleksa Sarai
2024-10-09 20:40 ` [PATCH RFC v3 02/10] sched_getattr: port to copy_struct_to_user Aleksa Sarai
2024-12-10 18:14   ` Florian Weimer [this message]
2024-12-11 10:23     ` Christian Brauner
2025-01-18 13:02       ` Xi Ruoyao
2025-01-20  5:28         ` Florian Weimer
2025-01-20  9:21           ` Xi Ruoyao
2025-01-20  9:51             ` Florian Weimer
2024-10-09 20:40 ` [PATCH RFC v3 03/10] openat2: explicitly return -E2BIG for (usize > PAGE_SIZE) Aleksa Sarai
2024-10-10  6:24   ` Greg KH
2024-10-10 10:09   ` (subset) " Christian Brauner
2024-10-09 20:40 ` [PATCH RFC v3 04/10] openat2: add CHECK_FIELDS flag to usize argument Aleksa Sarai
2024-10-09 20:40 ` [PATCH RFC v3 05/10] selftests: openat2: add 0xFF poisoned data after misaligned struct Aleksa Sarai
2024-10-09 20:40 ` [PATCH RFC v3 06/10] selftests: openat2: add CHECK_FIELDS selftests Aleksa Sarai
2024-10-09 20:40 ` [PATCH RFC v3 07/10] clone3: add CHECK_FIELDS flag to usize argument Aleksa Sarai
2024-10-09 20:40 ` [PATCH RFC v3 08/10] selftests: clone3: add CHECK_FIELDS selftests Aleksa Sarai
2024-10-09 20:40 ` [PATCH RFC v3 09/10] mount_setattr: add CHECK_FIELDS flag to usize argument Aleksa Sarai
2024-10-09 20:40 ` [PATCH RFC v3 10/10] selftests: mount_setattr: add CHECK_FIELDS selftest Aleksa Sarai
2024-10-10  6:26 ` [PATCH RFC v3 00/10] extensible syscalls: CHECK_FIELDS to allow for easier feature detection Florian Weimer
2024-10-21 14:51 ` (subset) " Christian Brauner
2024-10-21 21:38   ` Aleksa Sarai

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