From nobody Wed Feb 11 18:23:13 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1376DCA0EC3 for ; Mon, 11 Sep 2023 22:49:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240067AbjIKWpv (ORCPT ); Mon, 11 Sep 2023 18:45:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356189AbjIKWDI (ORCPT ); Mon, 11 Sep 2023 18:03:08 -0400 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D2EC1B1A3 for ; Mon, 11 Sep 2023 14:49:23 -0700 (PDT) Received: by mail-yb1-f202.google.com with SMTP id 3f1490d57ef6-d7e79ec07b4so4809384276.0 for ; Mon, 11 Sep 2023 14:49:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1694468808; x=1695073608; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=VtlA+KB8kDzwUN9dvFmpQoLjgzbj73lXqnrIpi3kP44=; b=G+QllVzkEPCPiNlCpw4eIWREaNMv1LfC5mrnsPFPy4Pc6VXkstKOW+LAK75+jr06XS nDyo1Cpmz8IMV52bX3gPhS5IZmxmw6pXSXCTxKG3hUXEiQPbmtPK4PeKlWUTJ2p+tLlD ie1dU6d6mGzTCjAS2vgKvVc9Kl4eWk41aIzhkaLxllJhyeFXspf72u1bC3CXl3LqVL9U xNLr/STpbc+ChtdKBOmW5Fvj5uwmVbr+ngdaZlkNMm8unx8Hufxwu2TmI9OJ30RM+YtW 3vbGFDFfoRmUlCqqLe30UndBNBrWysZzM6HImTqHYAgt/kJaMEboTn0KUYdKTF1Isd76 p0jA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694468808; x=1695073608; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=VtlA+KB8kDzwUN9dvFmpQoLjgzbj73lXqnrIpi3kP44=; b=BEOvlUFmegLVhz751QX72xxJzQhQpL1SqErxl2zaLIM/7GmAoNZrkvY2lzZsvZkygk DaF0WL78+AOQwA2evzZCjRVS4ZOiDhOKoI01RqgbhyCrMAdrSptlBGMM2ep61f+lkuPj 60jCUwE+v6vLcFZH/bITDkSMoXBUQhV+4a4z7gFjx/6RCsOL1VZW6BMWlJow3P9sAJW5 rgjNms4X59sgApZfAHYVhhB7+9pzXWvCoJx4BiHC45gex0k7219RbsocFLCMgdrSYTQC 4vbxSGEUTIStSKTaz8bFqteJ6MjTyKet1ZDUBhvD1/kC8FicHvs9LP0cx5G8WmfvYg/F j1uw== X-Gm-Message-State: AOJu0YwbBvtosAqvHR5g7w+8DYW5UC1VrPBNCK4nr3gufqwi7FUMtFZR DhOjQNB2F14QhppBzPibBEYRmRtbJbAU1uStNg== X-Google-Smtp-Source: AGHT+IGz+NEEOx+kTbptMq4j+qCzNxFKiPoF3JBZuUXHlbhZqlK9zFaMBms4PxAmrlhTc5ZEYgefWanCKL3AQYpMWA== X-Received: from jstitt-linux1.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:23b5]) (user=justinstitt job=sendgmr) by 2002:a05:6902:108f:b0:d78:3c2e:b186 with SMTP id v15-20020a056902108f00b00d783c2eb186mr249352ybu.5.1694468808319; Mon, 11 Sep 2023 14:46:48 -0700 (PDT) Date: Mon, 11 Sep 2023 21:46:47 +0000 Mime-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAMaK/2QC/x3NTQ6CQAxA4auQrm1CGX+CVzHEDEPVhrGQVomGc HcnLr/Neys4m7DDuVrBeBGXSQtoV0F6RL0zylAMTd2EuiVCf5mm+YuDycLm2OcpjajvnK99HvE ZRTHhKexbOgSmdIxQWrPxTT7/z6Xbth9z69SrdwAAAA== X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1694468807; l=2611; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=OWFJFfLu6R2MwsjnUT9XcLBqmI6CZTKqrnm0bDPTtIs=; b=LosAEspLXhaxEqoWCE/7ubiC5QsQX1wQYH8Q5dr8Rfy5EG7JDg1ORMnj9pREXDAE8Nr93Ab+Y J92caMRvcnwDaSGYgXwZQ8Lx07/ZJwt/KYaxiWbdy76qkHtaDS+f8AL X-Mailer: b4 0.12.3 Message-ID: <20230911-strncpy-drivers-block-null_blk-main-c-v1-1-3b3887e7fde4@google.com> Subject: [PATCH] null_blk: refactor deprecated strncpy From: Justin Stitt To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Kees Cook , Nick Desaulniers , Nathan Chancellor , Justin Stitt Content-Type: text/plain; charset="utf-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable `strncpy` is deprecated for use on NUL-terminated destination strings [1]. We should favor a more robust and less ambiguous interface. We know `nullb->disk_name` is NUL-terminated and we expect that `disk->disk_name` also be NUL-terminated: | snprintf(nullb->disk_name, sizeof(nullb->disk_name), | "%s", config_item_name(&dev->group.cg_item)); It seems like NUL-padding may be required due to __assign_disk_name() utilizing a memcpy as opposed to a `str*cpy` api. | static inline void __assign_disk_name(char *name, struct gendisk *disk) | { | if (disk) | memcpy(name, disk->disk_name, DISK_NAME_LEN); | else | memset(name, 0, DISK_NAME_LEN); | } This puzzles me as immediately after assigning the disk name we go and print it with `__print_disk_name` which wraps `nullb_trace_disk_name= ()`. | #define __print_disk_name(name) nullb_trace_disk_name(p, name) This function obviously expects a NUL-terminated string. | const char *nullb_trace_disk_name(struct trace_seq *p, char *name) | { | const char *ret =3D trace_seq_buffer_ptr(p); | | if (name && *name) | trace_seq_printf(p, "disk=3D%s, ", name); | trace_seq_putc(p, 0); | | return ret; | } I suspect that NUL-padding is _not_ needed but to be overly cautious let's use `strscpy_pad` (although I strongly suspect that whole memcpy thing should be changed). Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncp= y-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Cc: Kees Cook Cc: Nick Desaulniers Cc: Nathan Chancellor Signed-off-by: Justin Stitt --- Note: build-tested --- drivers/block/null_blk/main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c index 864013019d6b..994919c63f05 100644 --- a/drivers/block/null_blk/main.c +++ b/drivers/block/null_blk/main.c @@ -1938,7 +1938,7 @@ static int null_gendisk_register(struct nullb *nullb) else disk->fops =3D &null_bio_ops; disk->private_data =3D nullb; - strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN); + strscpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN); =20 if (nullb->dev->zoned) { int ret =3D null_register_zoned_dev(nullb); --- base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c change-id: 20230911-strncpy-drivers-block-null_blk-main-c-7349153e1c6a Best regards, -- Justin Stitt