From patchwork Fri Sep 22 11:49:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Justin Stitt X-Patchwork-Id: 13395659 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBA6E1F930 for ; Fri, 22 Sep 2023 11:49:22 +0000 (UTC) Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92CA5FB for ; Fri, 22 Sep 2023 04:49:21 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-d7fd4c23315so2530474276.2 for ; Fri, 22 Sep 2023 04:49:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1695383361; x=1695988161; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=ZXyxGhzRige3UrB4+p+4v9PuPDCzdTgmyjbIDA5ZLsI=; b=OHfFpdVsqTbk1xz2ltjUuf82IirAGWVU6a0u5Vgr21Kn+p8XJRTIfJEsRLm2XwJKbB lkdEQX+AwDUtZZEQkp6YlQ9dBspKJ1XbrKyWZiasCwsCi1MmKzsVOmfpX771aiorKCBE M7Q9+OusHbrTtosDsw73g8IIR2CaKm03GUkCZWbneGiVCt/NkcehxyHmoxCkguuOK7nD qFIORvX26lrL3EYToac+HS6knwKgC9omN/9ee/gHPQq7FJBZiNhH5RfLAKP0wttnswMO CQKNRMv+qqOszeX3E5kRsn4sjxPwvU3rB6szVwqdkS1J89BFhLAwMfABfKFg7vyqcBtq FJQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695383361; x=1695988161; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=ZXyxGhzRige3UrB4+p+4v9PuPDCzdTgmyjbIDA5ZLsI=; b=gr4ananUO6hIkLk782Lzpdjotnxm36oPYPZ7CYmWe+giM7IeEtdsIIHFplmW9SWjY0 au/3Y4Dg2SAMlT1ldmEmFhxiUH8pZxpNj9qzTsCb/CutC8vSSRZp/jCkCeH+Za9ls3St 9XEG5oZZhw0pUT64F8hW8lGd+dEXwBJDB4cEafQ9XdrL/jAUDzzLthW0eLqNG0fITZaQ o+JYNXbh0/65BPsLtPf1rRoGisjIixUXTtyb37C20QgJYbGXePWVtMshI00q0vbFWCV3 DWuCuq+xBxKlzu7Zma7m7jgQ2ZAYpsGPqX/ngk3lJWqHEHgRKBElClok0KOvIINpAPgu 2B+Q== X-Gm-Message-State: AOJu0Yxnwr3IN8XQdH6eD2VUbrc6geYcTCeFxvHnMBr2NKAHZKJ6sI6K pkTgWbRNE/h3ryAEHDjLuww1iXeyTf8z9KglaA== X-Google-Smtp-Source: AGHT+IElfQgQT6wbMncjFiA2exW2yO6eLXVY/tVVnaY3Q2kjEceLwN/PBhRPZKSywO8cyHS5x88dUl2JI+F/ZL/jrQ== X-Received: from jstitt-linux1.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:23b5]) (user=justinstitt job=sendgmr) by 2002:a5b:7c5:0:b0:d7f:f3e:74ab with SMTP id t5-20020a5b07c5000000b00d7f0f3e74abmr127533ybq.1.1695383360879; Fri, 22 Sep 2023 04:49:20 -0700 (PDT) Date: Fri, 22 Sep 2023 11:49:14 +0000 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-B4-Tracking: v=1; b=H4sIADl/DWUC/x2NQQqDMBAAvyJ77oKJxmq/UjxIsmmXQgy7RRTx7 4ZcBuYyc4KSMCm8mhOENlZeUxHzaMB/l/Qh5FAcbGu7drIW9S/J5wOD8EaiyBoS+iUz/io9OjN E84xuGsYeSicLRd7r4z1f1w2gXhc0cwAAAA== X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1695383359; l=2302; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=xmrjKIrKcccHwiQZLHhc+QD8XbzmyrFL8mHFb+Gfs4A=; b=qG0dzg9B6wVI/G86xbbk5dMi4zCmbwp8XMwL+vzCUiOwXjupj59HG/9MKVk0SHfEhICTweQTX Yx6PC25TXp1CgXLQZCRqikxujURFcztXUoBCmjwhvdV8dS45F85qshL X-Mailer: b4 0.12.3 Message-ID: <20230922-strncpy-drivers-isdn-capi-kcapi-c-v1-1-55fcf8b075fb@google.com> Subject: [PATCH] isdn: kcapi: replace deprecated strncpy with strscpy_pad From: Justin Stitt To: Karsten Keil Cc: netdev@vger.kernel.org, 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=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net `strncpy` is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. `buf` is used in this context as a data buffer with 64 bytes of memory to be occupied by capi_manufakturer. We see the caller capi20_get_manufacturer() passes data.manufacturer as its `buf` argument which is then later passed over to user space. Due to this, let's keep the NUL-padding that strncpy provided by using strscpy_pad so as to not leak any stack data. | cdev->errcode = capi20_get_manufacturer(data.contr, data.manufacturer); | if (cdev->errcode) | return -EIO; | | if (copy_to_user(argp, data.manufacturer, | sizeof(data.manufacturer))) | return -EFAULT; Perhaps this would also be a good instance to use `strtomem_pad` for but in my testing the compiler was not able to determine the size of `buf` -- even with all the hints. 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/isdn/capi/kcapi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- base-commit: 2cf0f715623872823a72e451243bbf555d10d032 change-id: 20230922-strncpy-drivers-isdn-capi-kcapi-c-516f17f59684 Best regards, -- Justin Stitt diff --git a/drivers/isdn/capi/kcapi.c b/drivers/isdn/capi/kcapi.c index ae24848af233..136ba9fe55e0 100644 --- a/drivers/isdn/capi/kcapi.c +++ b/drivers/isdn/capi/kcapi.c @@ -732,7 +732,7 @@ u16 capi20_get_manufacturer(u32 contr, u8 buf[CAPI_MANUFACTURER_LEN]) u16 ret; if (contr == 0) { - strncpy(buf, capi_manufakturer, CAPI_MANUFACTURER_LEN); + strscpy_pad(buf, capi_manufakturer, CAPI_MANUFACTURER_LEN); return CAPI_NOERROR; } @@ -740,7 +740,7 @@ u16 capi20_get_manufacturer(u32 contr, u8 buf[CAPI_MANUFACTURER_LEN]) ctr = get_capi_ctr_by_nr(contr); if (ctr && ctr->state == CAPI_CTR_RUNNING) { - strncpy(buf, ctr->manu, CAPI_MANUFACTURER_LEN); + strscpy_pad(buf, ctr->manu, CAPI_MANUFACTURER_LEN); ret = CAPI_NOERROR; } else ret = CAPI_REGNOTINSTALLED;