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[2001:1c00:3405:d100:1650:558:2e1d:372d]) by smtp.gmail.com with UTF8SMTPSA id a640c23a62f3a-b8037f519c0sm246666066b.71.2025.12.19.07.11.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Dec 2025 07:11:39 -0800 (PST) Date: Fri, 19 Dec 2025 16:11:39 +0100 From: Boudewijn van der Heide To: peterz@infradead.org Cc: mingo@redhat.com, will@kernel.org, boqun.feng@gmail.com, longman@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH] locking/lockdep: Fix string truncation and length accounting in seq_stats() Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" GCC 14 reports a -Wformat-truncation warning when appending "#%d" and "/%d" to the lock class name in seq_stats(), as the buffer size was insufficient and the resulting length was tracked incorrectly. Use scnprintf() with remaining-buffer accounting to safely append the suffixes and update namelen based on the actual number of characters written. Signed-off-by: Boudewijn van der Heide --- kernel/locking/lockdep_proc.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c index 1916db9aa46b..8fe977c32a3d 100644 --- a/kernel/locking/lockdep_proc.c +++ b/kernel/locking/lockdep_proc.c @@ -496,12 +496,14 @@ static void seq_stats(struct seq_file *m, struct lock= _stat_data *data) =20 namelen =3D strlen(name); if (class->name_version > 1) { - snprintf(name+namelen, 3, "#%d", class->name_version); - namelen +=3D 2; + namelen +=3D scnprintf(name + namelen, + sizeof(name) - namelen, "#%d", + class->name_version); } if (class->subclass) { - snprintf(name+namelen, 3, "/%d", class->subclass); - namelen +=3D 2; + namelen +=3D scnprintf(name + namelen, + sizeof(name) - namelen, "/%d", + class->subclass); } =20 if (stats->write_holdtime.nr) { --=20 2.47.3