From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpbgsg1.qq.com (smtpbgsg1.qq.com [54.254.200.92]) (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 7745741F5D7; Thu, 6 Aug 2026 08:49:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=54.254.200.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786006160; cv=none; b=t5eW969b9JJkK2SkbbpTfGHD3JxX1lDGs8Gd5UOC/6X4bV2sJZcEwP3pCLS87YYAuSvQ8+eTpyk3K3ZDSkqSrMAKBA04TnYFIIUhfzwqWzKtXJ0FZSPddF6LJ1VWDZYoGaN3tPG4+dy4YidSX+oUF6YGKmALC972CVfrMZ6GxEg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786006160; c=relaxed/simple; bh=bYVn57snV5A2ibN/w2p93lM39rQLKNNKwdn5GeNSJKk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=AbL3O5hraBYPt6wOTQg/EzIiTguJV1fjI+ez9wYwjMLepFVP6ENmf39SWL3ahmBcwh6fdmA5WeNljK9ep5FHx55fbvSpmhnAWo9katXz8dcLJED4WXyPyJBKJf2UREaFBCSe3Y5tcFi+wSX4FWaG63sOfTNB1BIvqSKMXGUi/rI= 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=aCC5lC0e; arc=none smtp.client-ip=54.254.200.92 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="aCC5lC0e" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uniontech.com; s=onoh2408; t=1786006153; bh=jUyYmBTsmqs0n3Z9OLd2hHj4Q6AzdFTzYfegDmaEhuU=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=aCC5lC0etUx/c+R+V9ajG2gUyWn/t16QIuhIGgl7EmG03GWgJe2b7Q/iBQqw0/ff3 /OMdSiSHcWHvHX/fZw9ER0sLjDoETHaCNdo6F9xx/crg6hxFsOyPchQUHZSytX7mh/ outJw+2Rk8hcKQyDVeCERIW+nvNk2rwNJbORY0E8= 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: linux-sound@vger.kernel.org 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: MFdGPHhuqhNo67/nlLyAYJWUdVghf09CvV+OMfNdOLweNCXKhS9Yf+Mu ayd5xDCMK9oHyEIiS8V7zoafQVzQkAsv5wcXKVUEtd7QdRhXZZNmI5kNMHrpaIwqn02cqZz 4LQ86jrcXgdfGAhycNLitxEYJRKgtZ32TfsO+/xUF7/fhGAqLa2k2Rui8jwOVpsRnv9kHxn qu/mAU5PlAtu0pAsMK7VVN3Wsw6y8pv10Zz6RNzNYTrpHY33cjaE986GzQH+0K1nz9EDRGv 6s4uUQNkQuE76ql089QjpqTuITb0BAqxWO3l5VjcdVArqfFq/yjFdtFMl1mhHeg3UrB2Ef0 fI7e6d3G8y0IToBS3PUCnkg3CDNB9VkojD0fOjGEIMUkmItSGZsicMAwaxQP9xNN4zf3U4H 0tbpgdO0kvf75v3g2C/4NvWnLavRMYajLnJ/KlKnLsPrTWNRx44gCCc0rfywyVIPC+hyFkS XmKh0Xpw7Ao3lv7tQ/wH2bQ5fWLja1Ltb5PQBntwgLFroc4tdiD0op45/MeCl/+g65GicOl uznHKwCk9eCNLpV+2rW88MyeZoq0HvQJhNDdXHPGU9Dl2WWuKgkuVUkNwKvNbMjwefB64qr 3Xu74+JkvLNOywaKF/6C6dLTeI7aFaZlnXAawb4Ks7Gp8C/jwGlPPrPgGIces+aXVUQJrdE w1HDenCnTh5fdc+dHAWCIR5oDn2VKvCDRbDVB26SnUjyjBjFsIqSECzmJBEtBKcDCQHjYxc y3M5KslnlgKyeLGHAiXWwfHsfky+WflOOibSVKnJavx5nLDszF4NnnYdxsah9QT/1RGPAVQ 3z6kYxbZIZUVKtaEjm8YiODQPdvw56v3ELYqBKTwdmhch3Fu5voyqF+9nAX5zoHsLSXinJR 1FoziAC8ysD32VWvQsP913jQd7lZXlfKXG8HYdiZW0qPyqqJhpXQHKy7gzrKtcmuqL922j6 doWnSWNyqc93kZIGzLZTp7O6MeZQ3aCpbd7skKOrdv0POPdVVvWFynubpAT0NGi1nKlV3cC B+5yUmXpvYfC7UUE4/OhkDWeMRwuI= X-QQ-XMRINFO: OD9hHCdaPRBwH5bRRRw8tsiH4UAatJqXfg== 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