From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f43.google.com (mail-ot1-f43.google.com [209.85.210.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 453D73232 for ; Mon, 31 Mar 2025 23:31:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743463883; cv=none; b=kNiVqOfyxLMBtwbUHUH2WVx7TckwlUSmILh9MR1C+l/VddQ97aWGuf4sUA0i5VHjvv5ETKsfP+qrV5ZpGE28SrJxuj60qzs2Abk9G5TsNQ9vP9IYe/hslNbGQMxjagplUPTDHCBlRT3GRWcZI/pvxBehdV2+nHkvnO8Un0AZvH0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743463883; c=relaxed/simple; bh=sUwfTHOCw9ZhqXto7fQMfJGGtRziqbuwKy80hrXngmQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qmRvZf4tNEHzOrYSXEQGPpQT1lSeyGpPhj25xY1qPP7ThPl41pqYqbgnI6YRvfC3CJqjzOBj3dzQk48EgYckP94YtzH1oFTx3ChZSOz9OrmJPCtJld+KB73oFQhDFlGgTnznimz35Snp+IGAKobQLS669+1yMDmZ5B6Isemgi2U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ieee.org; spf=pass smtp.mailfrom=ieee.org; dkim=pass (1024-bit key) header.d=ieee.org header.i=@ieee.org header.b=HeGZWZBR; arc=none smtp.client-ip=209.85.210.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ieee.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ieee.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ieee.org header.i=@ieee.org header.b="HeGZWZBR" Received: by mail-ot1-f43.google.com with SMTP id 46e09a7af769-72bd5f25ea6so1189441a34.1 for ; Mon, 31 Mar 2025 16:31:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ieee.org; s=google; t=1743463880; x=1744068680; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=xJ+toMwTx18/8SXmfnJl/GpEKdrIgAfy+X1oEZCBOJg=; b=HeGZWZBRCcz4fyjMzFUCPzICCRT3nVRgQczfjGB0NbtRehea9zLJKebhts3Y9rkjxx IMiJEVIsu+mFGmdgBCHG1o++T1TB8F7VNsY5BSKDvLgtvRmiYWdKGWuP4MGceknDsaID G376R/GsUaJhyIRtN3+atoO/aXi5PcJt4tst4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743463880; x=1744068680; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=xJ+toMwTx18/8SXmfnJl/GpEKdrIgAfy+X1oEZCBOJg=; b=AKeloZ7lXOhXvo8tQ7lY7BJLKe/4BCCTmeetOU6BXNykRkAX92sd2132Xz159RKcwm 2ZxGzM95bJ1d83pM5nXYSmPhVm47bmOY4GEfKX3qgFN2jZkBnUJzqgch1Og5zd8V2rPV w9nTraVxgeeG75sQFk49BEMZVLJmpXq/f8YFeifjxEMSkjRhpr/viYkljmu3cwCg50Q0 ufYorkwrRfbM72ahR0HP88Ri24Zqqj/M8QFaGMzqEc+OD+WE8O7PBCoTIi8qKpoZ4zrv MO4SLJNE9eCpBQdlNc1u1e4Njtkn7libwOrvRt7EmkifYvlv4Zgv9zQy4Lkhnrb+7vVR qj/A== X-Forwarded-Encrypted: i=1; AJvYcCUW8Ue9CosTHbktKKHFifjp5HN/dJIOj9DbXJCHcuOeQZ/uvmyDG4V86COQCdx6g7OUM10aTHFu0q/Qle0=@vger.kernel.org X-Gm-Message-State: AOJu0YzrN81BbaLOfgUXUq4tH4m3NmGpiZEbzn4DhbpTjxLhzS7/Yr6m 16RLUSB/qxpdnFLR9GxLSyouGzlb8TockWiZFSEzODk5brB0k34vyLpxFHbKcQ== X-Gm-Gg: ASbGncs6qXlNdLe8ZfMvy10PmZfGKRomkmZkcDxyI3kEnMLZP4+KuzJLFYxHKooGLMP 33XtidDsi4oLQ4+gbSQrn5vxJflA9dUdTqr+1cCZDGBjq5oQqBEavQDwCRSJSkPaMqUXO56NzdU 4g62Hoo10K7Cy1AfciYJQ9xxhxHq+iF8kztZXbniU0WIkhNpTBUVIDuEdaMcKEtlVyeDwY0gVyM soljbStuT0gAYGHk0zIDVpKNWLWQbFkl6C0SpY/KvWaMtiTz3QOiic8MeJcs+xA3HYE7uFboa8N Ye1G4VFaroFskni3VKG0fThGoYgj91sJQ8wygMKc3Mdt3enFM3m+wrg8hqzFBa9FUC7yuEfkrl1 8d5E= X-Google-Smtp-Source: AGHT+IEwmB2bcjMGzxlQpjRzg7wCA5OuVgfgfv5l11OQr+T9wVt6H6VgPvMbOoFq7GQ9enxJDZiAfA== X-Received: by 2002:a05:6830:699b:b0:72c:320b:f76b with SMTP id 46e09a7af769-72c6376d027mr6148642a34.1.1743463880158; Mon, 31 Mar 2025 16:31:20 -0700 (PDT) Received: from [172.22.22.28] (c-73-228-159-35.hsd1.mn.comcast.net. [73.228.159.35]) by smtp.googlemail.com with ESMTPSA id 46e09a7af769-72c580cd6c5sm1662891a34.32.2025.03.31.16.31.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Mar 2025 16:31:18 -0700 (PDT) Message-ID: <8a68ab78-cf18-4937-a8b7-fb0fa41c9d53@ieee.org> Date: Mon, 31 Mar 2025 18:31:15 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] staging: greybus: Remove unnecessary NUL-termination checks To: Thorsten Blum , Viresh Kumar , Johan Hovold , Alex Elder , Greg Kroah-Hartman Cc: greybus-dev@lists.linaro.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org References: <20250331183935.1880097-2-thorsten.blum@linux.dev> Content-Language: en-US From: Alex Elder In-Reply-To: <20250331183935.1880097-2-thorsten.blum@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/31/25 1:39 PM, Thorsten Blum wrote: > Commit 18f44de63f88 ("staging: greybus: change strncpy() to > strscpy_pad()") didn't remove the now unnecessary NUL-termination > checks. Unlike strncpy(), strscpy_pad() guarantees that the destination > buffer is NUL-terminated, making the checks obsolete. Remove them. > > Signed-off-by: Thorsten Blum This looks good! Although the NUL-termination check isn't needed, it isn't safe to ignore the return value of strscpy_pad(). More below. In all cases, it looks like strscpy_pad() (and not just strscpy()) is the correct thing to call, because the pad bytes are passed either to user space, or supplied as part of a Greybus request message. > --- > drivers/staging/greybus/fw-management.c | 39 +------------------------ > 1 file changed, 1 insertion(+), 38 deletions(-) > > diff --git a/drivers/staging/greybus/fw-management.c b/drivers/staging/greybus/fw-management.c > index a47385175582..852c0830261f 100644 > --- a/drivers/staging/greybus/fw-management.c > +++ b/drivers/staging/greybus/fw-management.c > @@ -125,16 +125,6 @@ static int fw_mgmt_interface_fw_version_operation(struct fw_mgmt *fw_mgmt, > > strscpy_pad(fw_info->firmware_tag, response.firmware_tag); > > - /* > - * The firmware-tag should be NULL terminated, otherwise throw error but > - * don't fail. > - */ > - if (fw_info->firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] != '\0') { > - dev_err(fw_mgmt->parent, > - "fw-version: firmware-tag is not NULL terminated\n"); > - fw_info->firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] = '\0'; > - } Interesting this didn't return an error, while others below did. The sizes of the arrays passed to strscpy_pad() are not necessarily the same, so you should check for its return value. fw_info->firmware_tag is GB_FIRMWARE_U_TAG_MAX_SIZE=10 bytes response.firmware_tag is GB_FIRMWARE_TAG_MAX_SIZE=10 bytes also, but these could theoretically change independently. > - > return 0; > } > > @@ -154,15 +144,6 @@ static int fw_mgmt_load_and_validate_operation(struct fw_mgmt *fw_mgmt, > request.load_method = load_method; > strscpy_pad(request.firmware_tag, tag); > Here the maximum length of the tag is GB_FIRMWARE_U_TAG_MAX_SIZE bytes, and it may or may not be NUL-terminated. The size of request.firmware_tag is GB_FIRMWARE_TAG_MAX_SIZE. Again you can't be sure they're the same, and even if they are, the source could be truncated. > - /* > - * The firmware-tag should be NULL terminated, otherwise throw error and > - * fail. > - */ > - if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] != '\0') { > - dev_err(fw_mgmt->parent, "load-and-validate: firmware-tag is not NULL terminated\n"); > - return -EINVAL; > - } > - > /* Allocate ids from 1 to 255 (u8-max), 0 is an invalid id */ > ret = ida_alloc_range(&fw_mgmt->id_map, 1, 255, GFP_KERNEL); > if (ret < 0) { > @@ -250,15 +231,6 @@ static int fw_mgmt_backend_fw_version_operation(struct fw_mgmt *fw_mgmt, > > strscpy_pad(request.firmware_tag, fw_info->firmware_tag); > The size of request.firmware_tag is GB_FIRMWARE_TAG_MAX_SIZE bytes. The size of fw_info->firmware_tag is GB_FIRMWARE_U_TAG_MAX_SIZE bytes. Check the return value for -E2BIG. > - /* > - * The firmware-tag should be NULL terminated, otherwise throw error and > - * fail. > - */ > - if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] != '\0') { > - dev_err(fw_mgmt->parent, "backend-version: firmware-tag is not NULL terminated\n"); > - return -EINVAL; > - } > - > ret = gb_operation_sync(connection, > GB_FW_MGMT_TYPE_BACKEND_FW_VERSION, &request, > sizeof(request), &response, sizeof(response)); > @@ -301,16 +273,7 @@ static int fw_mgmt_backend_fw_update_operation(struct fw_mgmt *fw_mgmt, > struct gb_fw_mgmt_backend_fw_update_request request; > int ret; > > - ret = strscpy_pad(request.firmware_tag, tag); > - > - /* > - * The firmware-tag should be NULL terminated, otherwise throw error and > - * fail. > - */ > - if (ret == -E2BIG) { > - dev_err(fw_mgmt->parent, "backend-update: firmware-tag is not NULL terminated\n"); > - return -EINVAL; > - } > + strscpy_pad(request.firmware_tag, tag); The size of request.firmware_tag is GB_FIRMWARE_TAG_MAX_SIZE bytes. The maximum size of tag is GB_FIRMWARE_U_TAG_MAX_SIZE bytes, and it may or may not be NUL-terminated. So this case should stay as-is, and check for -E2BIG. -Alex > /* Allocate ids from 1 to 255 (u8-max), 0 is an invalid id */ > ret = ida_alloc_range(&fw_mgmt->id_map, 1, 255, GFP_KERNEL);