From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpbgjp3.qq.com (smtpbgjp3.qq.com [54.92.39.34]) (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 043F23FC5B5 for ; Thu, 6 Aug 2026 08:49:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=54.92.39.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786006184; cv=none; b=IaBlGzmPHzVD7pv733PjRqj9o2noCCp7dI13/BFdiPzwnbs1tLPvgWLZqFAdSyAaScAa0OwkGHj1zNVlchZI4IG1PTem2G06O6fHW0G+bizCFN9i7LC22xELI8OvgM3PJDYO4gG2GS5JQEfW9QD+svxKFgEJV8nNcqZUkA7jeDE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786006184; c=relaxed/simple; bh=bYVn57snV5A2ibN/w2p93lM39rQLKNNKwdn5GeNSJKk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=nHV9fgDXwStCRiFBSHOduYaxSInSP62kluOd9lQBmv7hirdr4eYYlqN9/29oCNNIWOBXIL1bIac28QtfDiOEFZyCFRk5u02vtkibepgZo4r67JLqH1D+Yp0nHlOvk2woqTGLhf0QBHwtzYHlRQp0BfQFvjRbEHmuBv4+1qf23s8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uniontech.com; spf=pass smtp.mailfrom=uniontech.com; dkim=pass (1024-bit key) header.d=uniontech.com header.i=@uniontech.com header.b=TY2F0cFK; arc=none smtp.client-ip=54.92.39.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uniontech.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=uniontech.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=uniontech.com header.i=@uniontech.com header.b="TY2F0cFK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uniontech.com; s=onoh2408; t=1786006154; bh=jUyYmBTsmqs0n3Z9OLd2hHj4Q6AzdFTzYfegDmaEhuU=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=TY2F0cFKeX61LRRhufNlwe6FQvycX2zlbQWxfwLrhR47N3DfJ/4NB5+CnKSKEgzca D6pDvJZIt9iLIjW0wYbMLLzsx6sxAlE7mBr9zp9xQjuPfwEI9lgGEJBypkTr7Nj0YU yWdzYZz97Vu8b8NDznF1aouwkS7Ld0q6TgS6+53M= X-QQ-mid: esmtpgz10t1786006148t22d80378 X-QQ-Originating-IP: D2JFE83FYkgCrQbhtgVWxiQGpFIeUpgu08ldEDCPt7U= Received: from uniontech.com ( [113.57.152.160]) by bizesmtp.qq.com (ESMTP) with id ; Thu, 06 Aug 2026 16:49:06 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 1 X-BIZMAIL-ID: 736460180246486777 EX-QQ-RecipientCnt: 13 From: Yichong Chen To: gregkh@linuxfoundation.org Cc: rafael@kernel.org, dakr@kernel.org, djakov@kernel.org, quic_mdtipton@quicinc.com, vkoul@kernel.org, yung-chuan.liao@linux.intel.com, pierre-louis.bossart@linux.dev, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-sound@vger.kernel.org, Yichong Chen Subject: [PATCH v2 2/3] soundwire: debugfs: replace writable string helper Date: Thu, 6 Aug 2026 16:48:53 +0800 Message-Id: <20260806084854.1019789-3-chenyichong@uniontech.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20260806084854.1019789-1-chenyichong@uniontech.com> References: <20260806084854.1019789-1-chenyichong@uniontech.com> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: esmtpgz:uniontech.com:qybglogicsvrgz:qybglogicsvrgz3a-0 X-QQ-XMAILINFO: Mm/8i8/T4yneonnyiX7T3B4fEjZxZpO0mv8jmi4AE13nuEdSs9GAJldI 6QO/wG3SwO4i9LesVnr5pKWLhElxU2YiJG1C5vEvi6/J2oHMil6yiVQXbBawADcuwhEveS+ 8fMmXVNvKqSaVIMIsq3DQ9Xinp4998OLye/ae1jkjyUF3X/4Q8jOOgIxl6LiqiU3GgE1rEP xPL+C4sbhfUQtg240HmtmUmzUlLgQLQv7I/505D0xbp0L2B9pOrCto2rNau4XlkM7RppzAI KKuxq6B6sVAHAvTy3O0MaC/alvg2lZwKYKsEWyEhK1/QikIEYyiqdRX8/O2ZnVp+n7rUORs IGBGm2vjIqD1SoBUPgE2UMTQGWFxC1kR9x5CxB/v5OT6SQvPmN2TeUr47WUorT5wRa+EfQi OCb110gp1pkOPV2tbVlwJoL5BSrhhRxg0j0lundRZVAVRHB26G7KQcD0p0zNHeXJYDSUeUS gv8QuYogf1BFrRnDUeI246GoPT8DpQmnHTamAx9syl0NJJTVOJwGqrfPxQzZMEXN9NLA7up eL7+j24uF0YKpbFt2LkEZCjFVR2uZDZFWVDc9v6OjlG8T/fZRpDgg7sxYc5mdi51eJhAYi4 E5hIC8RsDa/p1otcPDAj8ajxI+nW9HnpnpBTPOilNuCaxJqdlvvIQDItmYDXSiHe0RxvKeY EF0WcwfbvqOUFvylvargqZLjU8H8JP25EGaPTJ3uDvrPYaeOyfDOwRE+MHPpqzq7nQSpa/J wIfbn1PcU36sHwHJ3CDBGgtgfpeQTGtXwlP+zMAX+OgzNsZAGP5Q1ugFdEWZcaMWSiWFsb7 7XUznynjTmE67V7NqZECGag4EA/k+DF3WKv0IxpuwQnvQ1hzdL9W61ZmnMR03H85kdAVsRt w6yDqizU/4G0Br2syz0sLcWYoU4Q/6swJbTslLDL//EzJ7Yl2etsQ624RmRIVS4OOA4M8Z0 uLjCInbFe5wAkHrFTo54diQsBI9rCmuCArhfBCQMg12M/V73ZbcZJtw/x79r1EKV64WDoGC R4PIw2sJvcHPilRUImqDc3G1Q67WE= X-QQ-XMRINFO: M/715EihBoGS47X28/vv4NpnfpeBLnr4Qg== X-QQ-RECHKSPAM: 0 debugfs_create_str() is being made read-only because its generic write path is hard to make safe without adding more locking to the helper. Convert the SoundWire firmware_file entry to a local write-only file operation before removing writable string support from debugfs_create_str(). Copy the firmware name before request_firmware() so later debugfs writes cannot replace the string while it is being used. Signed-off-by: Yichong Chen --- drivers/soundwire/debugfs.c | 56 ++++++++++++++++++++++++++++++++++--- 1 file changed, 52 insertions(+), 4 deletions(-) diff --git a/drivers/soundwire/debugfs.c b/drivers/soundwire/debugfs.c index 099eb84a548e..bba2b65a0668 100644 --- a/drivers/soundwire/debugfs.c +++ b/drivers/soundwire/debugfs.c @@ -145,6 +145,38 @@ static u32 start_addr; static size_t num_bytes; static u8 read_buffer[MAX_CMD_BYTES]; static char *firmware_file; +static DEFINE_MUTEX(firmware_file_lock); + +static ssize_t firmware_file_write(struct file *file, + const char __user *user_buf, + size_t count, loff_t *ppos) +{ + char *old, *new; + + if (*ppos) + return -EINVAL; + if (count + 1 > PAGE_SIZE) + return -E2BIG; + + new = memdup_user_nul(user_buf, count); + if (IS_ERR(new)) + return PTR_ERR(new); + strim(new); + + mutex_lock(&firmware_file_lock); + old = firmware_file; + firmware_file = new; + mutex_unlock(&firmware_file_lock); + + kfree(old); + return count; +} + +static const struct file_operations firmware_file_fops = { + .open = simple_open, + .write = firmware_file_write, + .llseek = default_llseek, +}; static int set_command(void *data, u64 value) { @@ -246,6 +278,7 @@ static int cmd_go(void *data, u64 value) { const struct firmware *fw = NULL; struct sdw_slave *slave = data; + char *fw_name = NULL; ktime_t start_t; ktime_t finish_t; int ret; @@ -265,15 +298,24 @@ static int cmd_go(void *data, u64 value) } if (cmd == 0) { - ret = request_firmware(&fw, firmware_file, &slave->dev); + mutex_lock(&firmware_file_lock); + if (firmware_file) + fw_name = kstrdup(firmware_file, GFP_KERNEL); + mutex_unlock(&firmware_file_lock); + if (!fw_name) { + ret = -ENOMEM; + goto out; + } + + ret = request_firmware(&fw, fw_name, &slave->dev); if (ret < 0) { - dev_err(&slave->dev, "firmware %s not found\n", firmware_file); + dev_err(&slave->dev, "firmware %s not found\n", fw_name); goto out; } if (fw->size < num_bytes) { dev_err(&slave->dev, "firmware %s: firmware size %zd, desired %zd\n", - firmware_file, fw->size, num_bytes); + fw_name, fw->size, num_bytes); goto out; } } @@ -306,6 +348,7 @@ static int cmd_go(void *data, u64 value) out: if (fw) release_firmware(fw); + kfree(fw_name); pm_runtime_mark_last_busy(&slave->dev); pm_runtime_put(&slave->dev); @@ -358,7 +401,8 @@ void sdw_slave_debugfs_init(struct sdw_slave *slave) debugfs_create_file("read_buffer", 0400, d, slave, &read_buffer_fops); if (firmware_file) - debugfs_create_str("firmware_file", 0200, d, &firmware_file); + debugfs_create_file("firmware_file", 0200, d, NULL, + &firmware_file_fops); slave->debugfs = d; } @@ -370,8 +414,10 @@ void sdw_slave_debugfs_exit(struct sdw_slave *slave) void sdw_debugfs_init(void) { + mutex_lock(&firmware_file_lock); if (!firmware_file) firmware_file = kstrdup("", GFP_KERNEL); + mutex_unlock(&firmware_file_lock); sdw_debugfs_root = debugfs_create_dir("soundwire", NULL); } @@ -379,6 +425,8 @@ void sdw_debugfs_init(void) void sdw_debugfs_exit(void) { debugfs_remove_recursive(sdw_debugfs_root); + mutex_lock(&firmware_file_lock); kfree(firmware_file); firmware_file = NULL; + mutex_unlock(&firmware_file_lock); } -- 2.51.0