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b=H4sIALouEWUC/x3MQQqEMAwAwK9Izgbaiqj7lcWDpFEDWiUR2UX8u 8XjXOYCYxU2+BQXKJ9isqUMXxZA85AmRonZEFyoXBdqtEMT7X+MKier4RoxrigbHQsS8lCTd9w 0XeshH7vyKL/3//b3/QDRb0d9bwAAAA== X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1695624891; l=2033; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=Xzkm/GfG5TixyIwt6w7TZiwEMeENCaF2BkA9N23/JYw=; b=Pll71UQQ271YXI/KDgT1SxB3YKLk0+/ZGgantJ+FeHwnT8xz+5ogZmc5HFnm704SlWm1akCpq lljdGZ0RX37DLGe4jPvoXlZJ0ncg6zPG3SltsZPVIXUsB9kS4PDBH/N X-Mailer: b4 0.12.3 Message-ID: <20230925-strncpy-drivers-md-dm-ioctl-c-v1-1-f0bfa093ef14@google.com> Subject: [PATCH] dm ioctl: replace deprecated strncpy with strscpy_pad From: Justin Stitt To: Alasdair Kergon , Mike Snitzer , dm-devel@redhat.com Cc: linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Justin Stitt X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Sun, 24 Sep 2023 23:55:13 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1778000142104830468 X-GMAIL-MSGID: 1778000142104830468 `strncpy` is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. We expect `spec->target_type` to be NUL-terminated based on its use with a format string after `dm_table_add_target()` is called | r = dm_table_add_target(table, spec->target_type, | (sector_t) spec->sector_start, | (sector_t) spec->length, | target_params); ... wherein `spec->target_type` is passed as parameter `type` and later printed with DMERR: | DMERR("%s: %s: unknown target type", dm_device_name(t->md), type); It appears that `spec` is not zero-allocated and thus NUL-padding may be required in this ioctl context. Considering the above, a suitable replacement is `strscpy_pad` due to the fact that it guarantees NUL-termination whilst maintaining the NUL-padding behavior that strncpy provides. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Reviewed-by: Kees Cook --- Note: build-tested only. --- drivers/md/dm-ioctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- base-commit: 6465e260f48790807eef06b583b38ca9789b6072 change-id: 20230925-strncpy-drivers-md-dm-ioctl-c-ea5c10e77981 Best regards, -- Justin Stitt diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 21ebb6c39394..e65058e0ed06 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1295,8 +1295,8 @@ static void retrieve_status(struct dm_table *table, spec->status = 0; spec->sector_start = ti->begin; spec->length = ti->len; - strncpy(spec->target_type, ti->type->name, - sizeof(spec->target_type) - 1); + strscpy_pad(spec->target_type, ti->type->name, + sizeof(spec->target_type)); outptr += sizeof(struct dm_target_spec); remaining = len - (outptr - outbuf);