From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpbgsg2.qq.com (smtpbgsg2.qq.com [54.254.200.128]) (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 2945B3FA5DD for ; Fri, 7 Aug 2026 10:03:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=54.254.200.128 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786096998; cv=none; b=jdM1mMEiVCqtAKt/Yw3hyGeLP6lwFG9uZWWNiT5lLZt4nuX33Gikf734ouIgwfPsHGsp57SKxIfirXXTDBzdD+JiqdOS3Gf1yntqOBNlItclvrrbgoWrEf+tgRB2ioYmSNwKqI1PAb3rDTTBxQZiqEHrIJuFvjL7V1GeGrzhk+A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786096998; c=relaxed/simple; bh=sTB+q2yGXMUFFVb/puERdZJCmbQ4/NCEbjGWkoO3doQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=EbLseGCy6BzMwrOSTbneR6tF4CZWFWI9Kmw4jpI1D8EZW1vrugjPWp837Egz1TyBkUYownWQlZfTE8aFqyQEXxA7lo8ObQ2ldlXVY7jAEE/lWD1rjW7xZ2SO+LJOKci2lrn79EglgPxPCArrM/AduXSPIdDIrF9P4+YYZmEm6Ks= 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=RT68QvRk; arc=none smtp.client-ip=54.254.200.128 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="RT68QvRk" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uniontech.com; s=onoh2408; t=1786096943; bh=MsDLrJziY9sfCbxEdR4Mn3VYin9jFIv1p9TVwvNq7cs=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=RT68QvRkmS6GFP8VPC9D7ibZzoyK8U6EMDrk4mRWVnOU+SxSGPsaRkZCr8Ht4mNVR 0yv/qgsG4JiDW+w1UtEvqgupnbLa07BPfx5tasB4rCYVfzHymaoa7FB/4FKOc9egX4 9yg+TVLrcLTEQJodUGWy1KwgTa04OzKYBquifvgY= X-QQ-mid: zesmtpgz1t1786096938ta3e5e1b1 X-QQ-Originating-IP: S+p1emIyL/pTOuj2FrBZ+LochIXhVzo8lbfR6Q1S5xI= Received: from uniontech.com ( [113.57.152.160]) by bizesmtp.qq.com (ESMTP) with id ; Fri, 07 Aug 2026 18:02:11 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 1 X-BIZMAIL-ID: 17825993322717190689 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 v3 2/3] soundwire: debugfs: replace writable string helper Date: Fri, 7 Aug 2026 18:00:52 +0800 Message-Id: <20260807100053.1089834-3-chenyichong@uniontech.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20260807100053.1089834-1-chenyichong@uniontech.com> References: <20260807100053.1089834-1-chenyichong@uniontech.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: zesmtpgz:uniontech.com:qybglogicsvrgz:qybglogicsvrgz3a-0 X-QQ-XMAILINFO: OA2DBih+LDLYVK7oeHVVfRU49+8yVsgq6Nc882r/c02Lqha8hJ0CwQxt k8WdY7b822R56V+KuquFFDoQO4YpzeT7Sx5nJmkCr/wbix6eU3p0j3yk+MfQk7GFSPKwegR VELqTXf5hfcCRn38KhHILMwDOhwilPx4n33Fj+vyFiFmxbMESIFtaGakY+FcigCge5bg15E d5oIbvcmQE9O1yCdBo68RPc876j0p54uXPlMMVNhikuMJLfQIomZBP4WoDLJhTP9pua41x5 FQePKfRmz67sK33Xwq+UBY2BnyGwqH4+GxCc1vYIvnXpoaegJrpR8tQIW1KUBvLvrADnZ0/ PGLVcRZuKpeLYpUp6dTVkfLaMyOTmBCD9KeSRzTUqOaybnEgqizSxS85arF3K2fDlEffDIz myD7/ea95EdYFA0p2ynNlvIzZsFRaKinWN6Jta0pvwU8CBHUNTmNdxSZ4f7mpCmC/hLdwDM zKAouLW1uijtvaz5dfthuLLuY/cMpgkQyshdBKm5lN6cp83oMXAaoQXZhPvj9EeWtvJ/LPh 50fDHTMadoyXP8+IS/n5uAp/WDe0ljUtH2oCbeC3r1E7Xel491Gnk2zVqJbIOIxRsNpvfmX WqyAaEY8NESPahvQiBA+66Xxl+m4L7fb6Peco0qNfGSbz2YvQAve/NEioh9lj2qfcnojo7b Xts4dETBfidSwh0QWUOALTO29qzciV0HJO//fcGQXQ17blYIQ6yiNRmQJWqJVPgAYU5SgUM t6GEsM8c8pMPpeKkQE9IRyzVM1ysi/zU7WtXvKFhu090UCnAzDNnK1fNLepfXaU+fum7bIo cf8cj/Dxn68J1zB+DSgMtUp+G8P3/sYRSFR5tpcYWLu4bxB4JoxdlnJYuoWQaBDX8WiZJW3 TVQZ/U+7ZNo0niVweBOiTJ5krNxoQhz+vrzgsQ5iz+ZHdzJw2RenjHCfffxvhVlTFO15WYd V2rivyZZzIG5HmBRHAE972U4QhBnaTzR1G9g7PyzNYioLb5v+rVq3ZDBvb4vsxWQnXrD1OQ w7xOxLb8rRMrk+P52NeBM8+5D8iaNo8oYlsGM2su9dGZvE1EKVIhLD9YUOd3igfGbPVXcyv XaLGZ0UX9TKlAJ5b+VS4+CqEX/DIaVL7yK3ILeuUz18nIpRwFRpa8TGcFLnwaITC8I07XFy EYjk X-QQ-XMRINFO: MPJ6Tf5t3I/ylTmHUqvI8+Wpn+Gzalws3A== 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 | 63 ++++++++++++++++++++++++++++++++----- 1 file changed, 55 insertions(+), 8 deletions(-) diff --git a/drivers/soundwire/debugfs.c b/drivers/soundwire/debugfs.c index 099eb84a548e..a8a6db164fe7 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); + + scoped_guard(mutex, &firmware_file_lock) { + old = firmware_file; + firmware_file = new; + } + + 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); + scoped_guard(mutex, &firmware_file_lock) { + if (firmware_file) + fw_name = kstrdup(firmware_file, GFP_KERNEL); + } + 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) { - if (!firmware_file) - firmware_file = kstrdup("", GFP_KERNEL); + scoped_guard(mutex, &firmware_file_lock) { + if (!firmware_file) + firmware_file = kstrdup("", GFP_KERNEL); + } sdw_debugfs_root = debugfs_create_dir("soundwire", NULL); } @@ -379,6 +425,7 @@ void sdw_debugfs_init(void) void sdw_debugfs_exit(void) { debugfs_remove_recursive(sdw_debugfs_root); - kfree(firmware_file); - firmware_file = NULL; + scoped_guard(mutex, &firmware_file_lock) { + kfree(firmware_file); + } } -- 2.51.0