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h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=jRdYyCQIPrzoWk3yqSvHINHIOMhOzE/LSwUZLhN2DE2134XoUqzMFueQqbtvZBH6B +iekQ/ECNmAeiMGoBR4YZUYTIcLgntXbB7ISOet5AoaaWJUVHZCUEZ7O5aOB/gC0Ii oq/qONExx7g9NFJkfnbOXdwwXP37Im9Hc3DjoFexlgTto+AXXPxvbZMj+BEq7PL9YH JHdmskSuwhpuPSPyd/3P7FTD6YK22xFDhWo6t6UkQVR5ZVfGU4uCv+IzHprJNx22QL zOsb37fSQfsKj1GBoIMilY/fk+KQ56JCEeEWCEl9LjIiIPB3O2Hor/VlPJ1ZQZcyhG 1BUprXTYfcgNA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH] mm/damon/sysfs-schemes: hold damon_sysfs_lock in target_value_store() Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: "Andrew Morton" , damon@lists.linux.dev, linux-mm@kvack.org In-Reply-To: <20261020144726.88978-1-sj@kernel.org> References: <20261020144726.88978-1-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 20 Oct 2026 14:54:16 +0000 X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 415D7180009 X-Stat-Signature: 3hmr4wjukdeice1p5zh8sbjcrahu1ioi X-Rspam-User: X-Spam-Status: No, score=-11.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1792508059-345058 X-HE-Meta: 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 sFRbJ0Gc 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [High] mm/damon/sysfs-schemes: uninitialized stack read in target_value_s= tore() -- commit f43fea0015fcb1917385f72d150c59603a9ae43c Author: SJ Park mm/damon/sysfs-schemes: hold damon_sysfs_lock in target_value_store() This commit holds damon_sysfs_lock in target_value_store() while updating goal->target_value to prevent a time-of-check-to-time-of-use race with damon_sysfs_add_quota_score() that could result in a divide-by-zero. > diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c > index 8f083611741fd..55298a17b653a 100644 > --- a/mm/damon/sysfs-schemes.c > +++ b/mm/damon/sysfs-schemes.c > @@ -1355,7 +1355,13 @@ static ssize_t target_value_store(struct kobject *= kobj, > { > struct damos_sysfs_quota_goal *goal =3D container_of(kobj, struct > damos_sysfs_quota_goal, kobj); > - int err =3D kstrtoul(buf, 0, &goal->target_value); > + unsigned long target_value; > + int err =3D kstrtoul(buf, 0, &target_value); > + > + if (!mutex_trylock(&damon_sysfs_lock)) > + return -EBUSY; > + goal->target_value =3D target_value; > + mutex_unlock(&damon_sysfs_lock); > =20 > return err ? err : count; > } [Severity: High] What happens in target_value_store() if kstrtoul() fails (for example, returning -EINVAL or -ERANGE on malformed input) while damon_sysfs_lock is not contended? Since kstrtoul() leaves target_value untouched on error and err is not checked before acquiring the lock, wouldn't this overwrite goal->target_value with an uninitialized stack value (which could also be read back via target_value_show())? Should err be checked and returned immediately after kstrtoul()? [] --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261020144726.8897= 8-1-sj@kernel.org?part=3D1