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[72.110.123.76]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35bba5a2c60sm196240a91.9.2026.03.17.12.00.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 12:00:27 -0700 (PDT) From: Gui-Dong Han To: gregkh@linuxfoundation.org, dakr@kernel.org, rafael@kernel.org Cc: linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-sound@vger.kernel.org, akaieurus@gmail.com, me@ziyao.cc, Gui-Dong Han , yangshiguang Subject: [PATCH 1/4] debugfs: check for NULL pointer in debugfs_create_str() Date: Wed, 18 Mar 2026 02:59:10 +0800 Message-ID: <20260317185920.43387-2-hanguidong02@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260317185920.43387-1-hanguidong02@gmail.com> References: <20260317185920.43387-1-hanguidong02@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Passing a NULL pointer to debugfs_create_str() leads to a NULL pointer dereference when the debugfs file is read. Following upstream discussions, forbid the creation of debugfs string files with NULL pointers. Add a WARN_ON() to expose offending callers and return early. Fixes: 9af0440ec86e ("debugfs: Implement debugfs_create_str()") Reported-by: yangshiguang Closes: https://lore.kernel.org/lkml/2025122221-gag-malt-75ba@gregkh/ Suggested-by: Greg Kroah-Hartman Signed-off-by: Gui-Dong Han --- fs/debugfs/file.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 3376ab6a519d..a941d73251b0 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -1127,7 +1127,7 @@ static const struct file_operations fops_str_wo =3D { * directory dentry if set. If this parameter is %NULL, then the * file will be created in the root of the debugfs filesystem. * @value: a pointer to the variable that the file should read to and write - * from. + * from. This pointer and the string it points to must not be %NUL= L. * * This function creates a file in debugfs with the given name that * contains the value of the variable @value. If the @mode variable is so @@ -1136,6 +1136,9 @@ static const struct file_operations fops_str_wo =3D { void debugfs_create_str(const char *name, umode_t mode, struct dentry *parent, char **value) { + if (WARN_ON(!value || !*value)) + return; + debugfs_create_mode_unsafe(name, mode, parent, value, &fops_str, &fops_str_ro, &fops_str_wo); } --=20 2.43.0 From nobody Mon Apr 6 21:32:18 2026 Received: from mail-pj1-f48.google.com (mail-pj1-f48.google.com [209.85.216.48]) (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 EEEA53F7AA5 for ; Tue, 17 Mar 2026 19:00:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.48 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773774049; cv=none; b=JkbZm/ob/OKQuRygN4HJeeeA4iglI39HEApLo/bqLg/YoxWpUyKykMioy7ZDRnGcFgtE+R6gklWZNuFr4FrAZIw3LaQAHg8LOr1esM1YN7LWhhf5zcYrnWufBwjqjziExpqrC53V0dc2RD6pbzqCWB9Q+OQdeOSJoo9aFRocnxs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773774049; c=relaxed/simple; bh=u7g7PqC1ksiTGawd2FT2mK39JtKLQRmCXd42/gsT/iA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aU7NR20jIpcUwxbpZIDAl7l1e/FQhoLKe9XGzQ3cyjrHyjMmcI3Sw/buHNdvxHLi2hw+YQdz8V+7qX3DniK4ymBqy50w7FBCcXGylaji5aFHLKv57ooJ9YZxIDeCpMzwu9924No52gAaqKoyN14PsvEWrRkw9QVpw2Iog8i9UT4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=S/aJC8oo; arc=none smtp.client-ip=209.85.216.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="S/aJC8oo" Received: by mail-pj1-f48.google.com with SMTP id 98e67ed59e1d1-3585ec417f6so88770a91.1 for ; Tue, 17 Mar 2026 12:00:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1773774047; x=1774378847; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=G5pUoPYvzvdY/i+3VyCKmXdQJFa9RgqmeQepWrHmR+w=; b=S/aJC8oo2uH1NpB2KCo4H148SjNq/uPyfeOTEggqy8ayYRSp+NBvnhxn1KUUZvFQva aQkDxm/iJ+UB+qsQmNsOvZubapgkjvpPKLgkWkPxqBi/KAkrx3tA9HxAxwu5WmREp82M 3AEvZRuOT2Aj6gI2P5KoyfA+Qn1LHWuVm4rNQ/l4GIt1T66sJI+dYXSJpf9Vvcpy+yVU ZYNMZ8W8mmq3TEFmnRaECnM0+H/EyNkW5W7cn2LX7PU787tXrORaXe9Pz1HzVpcOO3qY 16ol3ZTZi735NfT7jWbE2X+wVofqxbxgaVm3Z9YzDimxgVUuPoH8zZvZAFckDtjaVOd1 53KA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773774047; x=1774378847; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=G5pUoPYvzvdY/i+3VyCKmXdQJFa9RgqmeQepWrHmR+w=; b=kBeTWfIXgdCz/K66383cg8qfRpppJjWsMPmr3qiQL2KNzjlCMheDhdUDIjXBvD+gDK xwi6s1lWlMk4Fo8YP/39znTi5QNeIvenxJGvngVONGOXL/669cZpVVE17Y8UTUq0ptRu y1zvlABahNpqDBIupmhcYURNqB/44pdfd+zOlytR5Cl7N+66PDZAch08ejPgYeONIMiX 80sAmhc0QwsQ9PnChsTYzbA9kmmzdo6f1lXgNLdftl/sdPAeNh/Wct0Ljf2MzxTJ58q5 HAVcx7ba+c84K2gyw/KyyPG+rA8tlWVeddpwdx7xb8dL8Vj08+zjPif3/WMAEbQpIFQl 9Rww== X-Gm-Message-State: AOJu0YzPxsAGmHmlQ1tJKsk/eLKeF6DXoXyDta3lK/K+Q5pGJyoB6wb4 bXVmaXY93f4+M08F9bu6F1hjBn70U2F4FOApAXeHuhqNARxYrHEne9W+ X-Gm-Gg: ATEYQzwr+E9Qa8tLnZGUexZchzUBgJVLScKR86QfZvJsJXAlC7Spp3flJVPof8f+7Tv m+XKgQ7/3AmX9jKj5Am8lfE4xG4RLafpBj+VyoNzkAlTniqeuEkaSrXZ/d5MM0L19nyDyyQiGj4 4pRoPRAo47Z0c0BiTRWsUFPhm9OsnVGJq/oxCqZjtSloJ7jeMGdTolV8Qw/XYbuUakxF4FdwPt0 vKiGdLPYXqaBMVLbewaoU+Qml4KIvh6RdDcL+IYcnMJJhlpQK+Qbtgb38dAUQOVU/RJPsso1YZu 6SVbRtwZr8OWbruvkUpVtKfhswkWe3X0zFdsOqx+vNKECv6ed/pLAzaaD/AhOMKYsX9EL6RNlz3 5re/vVwmq/jf3nA0vSLSOpD/yc1hjaImMKdKx68wHHPY7ihjl+VVf0aDut8NiEYXMev38O1QpOs fWGMqUkep2ZAeVQAGFug2MJh1BJc+53yf6e8rwvWDpD4VJwcSpmrMA4d0aIAKSFTJfvAiEcsrWZ IsrJ9g+zznvJF5/64+wWRFu/K6Xb3dn3NUc9Hi+AnrTfu3lim10Q3fddzVCWmZY2Kmejw== X-Received: by 2002:a17:90b:3a47:b0:35b:9f51:a755 with SMTP id 98e67ed59e1d1-35badc14391mr3481930a91.18.1773774047144; Tue, 17 Mar 2026 12:00:47 -0700 (PDT) Received: from 2045D.localdomain (76.sub-72-110-123.myvzw.com. [72.110.123.76]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35bba5a2c60sm196240a91.9.2026.03.17.12.00.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 12:00:46 -0700 (PDT) From: Gui-Dong Han To: gregkh@linuxfoundation.org, dakr@kernel.org, rafael@kernel.org Cc: linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-sound@vger.kernel.org, akaieurus@gmail.com, me@ziyao.cc, Gui-Dong Han Subject: [PATCH 2/4] debugfs: fix placement of EXPORT_SYMBOL_GPL for debugfs_create_str() Date: Wed, 18 Mar 2026 02:59:11 +0800 Message-ID: <20260317185920.43387-3-hanguidong02@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260317185920.43387-1-hanguidong02@gmail.com> References: <20260317185920.43387-1-hanguidong02@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The EXPORT_SYMBOL_GPL() for debugfs_create_str was placed incorrectly away from the function definition. Move it immediately below the debugfs_create_str() function where it belongs. Fixes: d60b59b96795 ("debugfs: Export debugfs_create_str symbol") Signed-off-by: Gui-Dong Han --- fs/debugfs/file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index a941d73251b0..edd6aafbfbaa 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -1047,7 +1047,6 @@ ssize_t debugfs_read_file_str(struct file *file, char= __user *user_buf, =20 return ret; } -EXPORT_SYMBOL_GPL(debugfs_create_str); =20 static ssize_t debugfs_write_file_str(struct file *file, const char __user= *user_buf, size_t count, loff_t *ppos) @@ -1142,6 +1141,7 @@ void debugfs_create_str(const char *name, umode_t mod= e, debugfs_create_mode_unsafe(name, mode, parent, value, &fops_str, &fops_str_ro, &fops_str_wo); } +EXPORT_SYMBOL_GPL(debugfs_create_str); =20 static ssize_t read_file_blob(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) --=20 2.43.0 From nobody Mon Apr 6 21:32:18 2026 Received: from mail-pf1-f180.google.com (mail-pf1-f180.google.com [209.85.210.180]) (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 1D3C126463A for ; 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[72.110.123.76]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82a6bf0cf5fsm224612b3a.61.2026.03.17.12.11.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 12:11:11 -0700 (PDT) From: Gui-Dong Han To: gregkh@linuxfoundation.org, dakr@kernel.org, rafael@kernel.org, vkoul@kernel.org, yung-chuan.liao@linux.intel.com Cc: pierre-louis.bossart@linux.dev, rander.wang@intel.com, linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-sound@vger.kernel.org, akaieurus@gmail.com, me@ziyao.cc, Gui-Dong Han , yangshiguang Subject: [PATCH 3/4] soundwire: debugfs: initialize firmware_file to empty string Date: Wed, 18 Mar 2026 03:10:29 +0800 Message-ID: <20260317191029.43515-1-hanguidong02@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260317185920.43387-1-hanguidong02@gmail.com> References: <20260317185920.43387-1-hanguidong02@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Passing NULL to debugfs_create_str() causes a NULL pointer dereference upon reading, and creating debugfs nodes with NULL string pointers is no longer permitted. Change the initialization of firmware_file to an allocated empty string. Existing driver code using this field handles empty strings correctly. Fixes: fe46d2a4301d ("soundwire: debugfs: add interface to read/write comma= nds") Reported-by: yangshiguang Closes: https://lore.kernel.org/lkml/17647e4c.d461.19b46144a4e.Coremail.yan= gshiguang1011@163.com/ Signed-off-by: Gui-Dong Han --- drivers/soundwire/debugfs.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/soundwire/debugfs.c b/drivers/soundwire/debugfs.c index ccc9670ef77c..d4abe8bfca76 100644 --- a/drivers/soundwire/debugfs.c +++ b/drivers/soundwire/debugfs.c @@ -358,8 +358,9 @@ void sdw_slave_debugfs_init(struct sdw_slave *slave) debugfs_create_file("go", 0200, d, slave, &cmd_go_fops); =20 debugfs_create_file("read_buffer", 0400, d, slave, &read_buffer_fops); - firmware_file =3D NULL; - debugfs_create_str("firmware_file", 0200, d, &firmware_file); + firmware_file =3D devm_kstrdup(&slave->dev, "", GFP_KERNEL); + if (firmware_file) + debugfs_create_str("firmware_file", 0200, d, &firmware_file); =20 slave->debugfs =3D d; } --=20 2.43.0 From nobody Mon Apr 6 21:32:18 2026 Received: from mail-pg1-f175.google.com (mail-pg1-f175.google.com [209.85.215.175]) (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 D4515158DA3 for ; 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[72.110.123.76]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c741e546b01sm334350a12.21.2026.03.17.12.16.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 12:16:27 -0700 (PDT) From: Gui-Dong Han To: gregkh@linuxfoundation.org, dakr@kernel.org, rafael@kernel.org, jani.nikula@linux.intel.com, rodrigo.vivi@intel.com, joonas.lahtinen@linux.intel.com, tursulin@ursulin.net, airlied@gmail.com, simona@ffwll.ch Cc: gustavo.sousa@intel.com, demarchi@kernel.org, jouni.hogander@intel.com, luciano.coelho@intel.com, linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-sound@vger.kernel.org, akaieurus@gmail.com, me@ziyao.cc, Gui-Dong Han Subject: [PATCH 4/4] drm/i915/display: initialize string params to empty strings Date: Wed, 18 Mar 2026 03:15:38 +0800 Message-ID: <20260317191538.43535-1-hanguidong02@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260317185920.43387-1-hanguidong02@gmail.com> References: <20260317185920.43387-1-hanguidong02@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Passing NULL to debugfs_create_str() causes a NULL pointer dereference upon reading, and is no longer permitted. Change the default values of dmc_firmware_path and vbt_firmware to empty strings (""). Existing code that consumes these parameters already verifies both pointer validity and string length, so empty strings are handled correctly. Furthermore, heap allocation is not required here: these debugfs parameters are created with strictly read-only permissions (0400). As a result, the debugfs write operation is never invoked, meaning the static empty string will not be erroneously freed by kfree(). Fixes: e9913f0bd2e1 ("drm/i915/display: move dmc_firmware_path to display p= arams") Fixes: 29292bc6cc37 ("drm/i915/display: Move vbt_firmware module parameter = under display") Signed-off-by: Gui-Dong Han --- drivers/gpu/drm/i915/display/intel_display_params.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_display_params.h b/drivers/= gpu/drm/i915/display/intel_display_params.h index b95ecf728daa..0a8cad98d480 100644 --- a/drivers/gpu/drm/i915/display/intel_display_params.h +++ b/drivers/gpu/drm/i915/display/intel_display_params.h @@ -23,8 +23,8 @@ struct drm_printer; * debugfs file */ #define INTEL_DISPLAY_PARAMS_FOR_EACH(param) \ - param(char *, dmc_firmware_path, NULL, 0400) \ - param(char *, vbt_firmware, NULL, 0400) \ + param(char *, dmc_firmware_path, "", 0400) \ + param(char *, vbt_firmware, "", 0400) \ param(int, lvds_channel_mode, 0, 0400) \ param(int, panel_use_ssc, -1, 0600) \ param(int, vbt_sdvo_panel_type, -1, 0400) \ --=20 2.43.0