From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Alejandro Colomar <alx@kernel.org>
Cc: linux-mm@kvack.org, linux-hardening@vger.kernel.org,
Kees Cook <kees@kernel.org>,
Christopher Bazley <chris.bazley.wg14@gmail.com>,
shadow <~hallyn/shadow@lists.sr.ht>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
kasan-dev@googlegroups.com, Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
Christoph Lameter <cl@linux.com>,
David Rientjes <rientjes@google.com>,
Vlastimil Babka <vbabka@suse.cz>,
Roman Gushchin <roman.gushchin@linux.dev>,
Harry Yoo <harry.yoo@oracle.com>
Subject: Re: [RFC v1 0/3] Add and use seprintf() instead of less ergonomic APIs
Date: Tue, 08 Jul 2025 08:43:57 +0200 [thread overview]
Message-ID: <87a55fw5aq.fsf@prevas.dk> (raw)
In-Reply-To: <cover.1751747518.git.alx@kernel.org> (Alejandro Colomar's message of "Sat, 5 Jul 2025 22:33:47 +0200")
On Sat, Jul 05 2025, Alejandro Colomar <alx@kernel.org> wrote:
> On top of that, I have a question about the functions I'm adding,
> and the existing kernel snprintf(3): The standard snprintf(3)
> can fail (return -1), but the kernel one doesn't seem to return <0 ever.
> Should I assume that snprintf(3) doesn't fail here?
Yes. Just because the standard says it may return an error, as a QoI
thing the kernel's implementation never fails. That also means that we
do not ever do memory allocation or similar in the guts of vsnsprintf
(that would anyway be a mine field of locking bugs).
If we hit some invalid or unsupported format specifier (i.e. a bug in
the caller), we return early, but still report what we wrote until
hitting that.
Rasmus
next prev parent reply other threads:[~2025-07-08 6:44 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-05 20:33 [RFC v1 0/3] Add and use seprintf() instead of less ergonomic APIs Alejandro Colomar
2025-07-05 20:33 ` [RFC v1 1/3] vsprintf: Add [v]seprintf(), [v]stprintf() Alejandro Colomar
2025-07-05 20:40 ` Alejandro Colomar
2025-07-07 9:47 ` Alexander Potapenko
2025-07-07 14:59 ` Alejandro Colomar
2025-07-05 20:33 ` [RFC v1 2/3] stacktrace, stackdepot: Add seprintf()-like variants of functions Alejandro Colomar
2025-07-05 20:33 ` [RFC v1 3/3] mm: Use seprintf() instead of less ergonomic APIs Alejandro Colomar
2025-07-05 21:54 ` Alejandro Colomar
2025-07-06 17:37 ` [RFC v2 0/5] Add and use " Alejandro Colomar
2025-07-06 17:37 ` [RFC v2 1/5] vsprintf: Add [v]seprintf(), [v]stprintf() Alejandro Colomar
2025-07-06 17:37 ` [RFC v2 2/5] stacktrace, stackdepot: Add seprintf()-like variants of functions Alejandro Colomar
2025-07-06 17:37 ` [RFC v2 3/5] mm: Use seprintf() instead of less ergonomic APIs Alejandro Colomar
2025-07-06 17:37 ` [RFC v2 4/5] array_size.h: Add ENDOF() Alejandro Colomar
2025-07-06 17:37 ` [RFC v2 5/5] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-07-07 5:06 ` [RFC v3 0/7] Add and use seprintf() instead of less ergonomic APIs Alejandro Colomar
2025-07-07 5:06 ` [RFC v3 1/7] vsprintf: Add [v]seprintf(), [v]stprintf() Alejandro Colomar
2025-07-07 5:06 ` [RFC v3 2/7] stacktrace, stackdepot: Add seprintf()-like variants of functions Alejandro Colomar
2025-07-07 5:06 ` [RFC v3 3/7] mm: Use seprintf() instead of less ergonomic APIs Alejandro Colomar
2025-07-07 7:44 ` Marco Elver
2025-07-07 14:39 ` Alejandro Colomar
2025-07-07 14:58 ` Marco Elver
2025-07-07 18:51 ` Alejandro Colomar
2025-07-07 19:08 ` Marco Elver
2025-07-07 20:53 ` Alejandro Colomar
2025-07-07 19:17 ` Linus Torvalds
2025-07-07 19:35 ` Al Viro
2025-07-07 20:46 ` Linus Torvalds
2025-07-07 20:29 ` Alejandro Colomar
2025-07-07 20:49 ` Linus Torvalds
2025-07-07 21:05 ` Alejandro Colomar
2025-07-07 21:26 ` Alejandro Colomar
2025-07-07 22:17 ` Linus Torvalds
2025-07-08 2:20 ` Alejandro Colomar
2025-07-12 20:58 ` Christopher Bazley
2025-07-14 7:57 ` Christopher Bazley
2025-07-07 5:06 ` [RFC v3 4/7] array_size.h: Add ENDOF() Alejandro Colomar
2025-07-07 5:06 ` [RFC v3 5/7] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-07-07 7:46 ` Marco Elver
2025-07-07 7:53 ` Michal Hocko
2025-07-07 14:42 ` Alejandro Colomar
2025-07-07 15:12 ` Michal Hocko
2025-07-07 15:29 ` Alejandro Colomar
2025-07-07 5:06 ` [RFC v3 6/7] sprintf: Add [V]STPRINTF() Alejandro Colomar
2025-07-07 5:06 ` [RFC v3 7/7] mm: Use [V]STPRINTF() to avoid specifying the array size Alejandro Colomar
2025-07-07 5:11 ` [RFC v3 0/7] Add and use seprintf() instead of less ergonomic APIs Alejandro Colomar
2025-07-10 2:47 ` [RFC v4 0/7] Add and use sprintf_end() " Alejandro Colomar
2025-07-10 2:47 ` alx-0049r2 - add seprintf() Alejandro Colomar
2025-07-10 2:48 ` [RFC v4 1/7] vsprintf: Add [v]sprintf_end() Alejandro Colomar
2025-07-10 2:48 ` [RFC v4 2/7] stacktrace, stackdepot: Add sprintf_end()-like variants of functions Alejandro Colomar
2025-07-10 2:48 ` [RFC v4 3/7] mm: Use sprintf_end() instead of less ergonomic APIs Alejandro Colomar
2025-07-10 2:48 ` [RFC v4 4/7] array_size.h: Add ENDOF() Alejandro Colomar
2025-07-10 2:48 ` [RFC v4 5/7] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-07-10 2:48 ` [RFC v4 6/7] sprintf: Add [V]SPRINTF_END() Alejandro Colomar
2025-07-10 15:52 ` Linus Torvalds
2025-07-10 18:30 ` Alejandro Colomar
2025-07-10 21:21 ` Alejandro Colomar
2025-07-10 22:08 ` Linus Torvalds
2025-07-10 2:49 ` [RFC v4 7/7] mm: Use [V]SPRINTF_END() to avoid specifying the array size Alejandro Colomar
2025-07-10 21:30 ` [RFC v5 0/7] Add and use sprintf_{end,array}() instead of less ergonomic APIs Alejandro Colomar
2025-07-10 21:30 ` [RFC v5 1/7] vsprintf: Add [v]sprintf_end() Alejandro Colomar
2025-07-10 21:30 ` [RFC v5 2/7] stacktrace, stackdepot: Add sprintf_end()-like variants of functions Alejandro Colomar
2025-07-10 21:30 ` [RFC v5 3/7] mm: Use sprintf_end() instead of less ergonomic APIs Alejandro Colomar
2025-07-10 21:31 ` [RFC v5 4/7] array_size.h: Add ENDOF() Alejandro Colomar
2025-07-10 21:31 ` [RFC v5 5/7] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-07-10 21:31 ` [RFC v5 6/7] sprintf: Add [v]sprintf_array() Alejandro Colomar
2025-07-10 21:58 ` Linus Torvalds
2025-07-10 23:23 ` Alejandro Colomar
2025-07-10 23:24 ` Alejandro Colomar
2025-07-11 0:19 ` Alejandro Colomar
2025-07-11 17:43 ` David Laight
2025-07-11 19:17 ` Alejandro Colomar
2025-07-11 19:21 ` Alejandro Colomar
2025-07-11 6:05 ` Martin Uecker
2025-07-11 6:19 ` Martin Uecker
2025-07-11 17:45 ` David Laight
2025-07-11 17:58 ` Linus Torvalds
2025-07-11 19:24 ` Matthew Wilcox
2025-07-15 5:19 ` Kees Cook
2025-07-15 6:24 ` Martin Uecker
2025-07-17 23:44 ` Kees Cook
2025-07-15 7:08 ` Alejandro Colomar
2025-07-17 23:47 ` Kees Cook
2025-07-18 0:56 ` Alejandro Colomar
2025-07-11 18:01 ` Martin Uecker
2025-07-10 21:31 ` [RFC v5 7/7] mm: Use [v]sprintf_array() to avoid specifying the array size Alejandro Colomar
2025-07-11 1:56 ` [RFC v6 0/8] Add and use sprintf_{end,trunc,array}() instead of less ergonomic APIs Alejandro Colomar
2025-07-11 1:56 ` [RFC v6 1/8] vsprintf: Add [v]sprintf_trunc() Alejandro Colomar
2025-07-11 1:56 ` [RFC v6 2/8] vsprintf: Add [v]sprintf_end() Alejandro Colomar
2025-07-11 1:56 ` [RFC v6 3/8] sprintf: Add [v]sprintf_array() Alejandro Colomar
2025-07-11 1:56 ` [RFC v6 4/8] stacktrace, stackdepot: Add sprintf_end()-like variants of functions Alejandro Colomar
2025-07-11 1:57 ` [RFC v6 5/8] mm: Use sprintf_end() instead of less ergonomic APIs Alejandro Colomar
2025-07-11 1:57 ` [RFC v6 6/8] array_size.h: Add ENDOF() Alejandro Colomar
2025-07-11 1:57 ` [RFC v6 7/8] mm: Fix benign off-by-one bugs Alejandro Colomar
2025-07-11 1:57 ` [RFC v6 8/8] mm: Use [v]sprintf_array() to avoid specifying the array size Alejandro Colomar
2025-07-08 6:43 ` Rasmus Villemoes [this message]
2025-07-08 11:36 ` [RFC v1 0/3] Add and use seprintf() instead of less ergonomic APIs Alejandro Colomar
2025-07-08 13:51 ` Rasmus Villemoes
2025-07-08 16:14 ` Alejandro Colomar
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