From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Bruce Chen <bruce.chen@unisoc.com>,
        Cixi Geng <cixi.geng1@unisoc.com>,
        Cixi Geng <gengcixi@gmail.com>,
        Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        Sasha Levin <sashal@kernel.org>, linux-usb@vger.kernel.org
Subject: [PATCH AUTOSEL 6.2 30/64] USB: dwc3: fix memory leak with using debugfs_lookup()
Date:   Fri,  3 Mar 2023 16:40:32 -0500
Message-Id: <20230303214106.1446460-30-sashal@kernel.org>
In-Reply-To: <20230303214106.1446460-1-sashal@kernel.org>
References: <20230303214106.1446460-1-sashal@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit be308d68785b205e483b3a0c61ba3a82da468f2c ]

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Note, the root dentry for the debugfs directory for the device needs to
be saved so we don't have to keep looking it up, which required a bit
more refactoring to properly create and remove it when needed.

Reported-by: Bruce Chen <bruce.chen@unisoc.com>
Reported-by: Cixi Geng <cixi.geng1@unisoc.com>
Tested-by: Cixi Geng <gengcixi@gmail.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/20230202152820.2409908-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/dwc3/core.h    |  2 ++
 drivers/usb/dwc3/debug.h   |  3 +++
 drivers/usb/dwc3/debugfs.c | 19 ++++++++-----------
 drivers/usb/dwc3/gadget.c  |  4 +---
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 8f9959ba9fd46..582ebd9cf9c2e 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1117,6 +1117,7 @@ struct dwc3_scratchpad_array {
  *		     address.
  * @num_ep_resized: carries the current number endpoints which have had its tx
  *		    fifo resized.
+ * @debug_root: root debugfs directory for this device to put its files in.
  */
 struct dwc3 {
 	struct work_struct	drd_work;
@@ -1332,6 +1333,7 @@ struct dwc3 {
 	int			max_cfg_eps;
 	int			last_fifo_depth;
 	int			num_ep_resized;
+	struct dentry		*debug_root;
 };
 
 #define INCRX_BURST_MODE 0
diff --git a/drivers/usb/dwc3/debug.h b/drivers/usb/dwc3/debug.h
index 48b44b88dc252..8bb2c9e3b9ac6 100644
--- a/drivers/usb/dwc3/debug.h
+++ b/drivers/usb/dwc3/debug.h
@@ -414,11 +414,14 @@ static inline const char *dwc3_gadget_generic_cmd_status_string(int status)
 
 #ifdef CONFIG_DEBUG_FS
 extern void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep);
+extern void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep);
 extern void dwc3_debugfs_init(struct dwc3 *d);
 extern void dwc3_debugfs_exit(struct dwc3 *d);
 #else
 static inline void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
 {  }
+static inline void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep)
+{  }
 static inline void dwc3_debugfs_init(struct dwc3 *d)
 {  }
 static inline void dwc3_debugfs_exit(struct dwc3 *d)
diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index f2b7675c7f621..850df0e6bcabf 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -873,27 +873,23 @@ static const struct dwc3_ep_file_map dwc3_ep_file_map[] = {
 	{ "GDBGEPINFO", &dwc3_ep_info_register_fops, },
 };
 
-static void dwc3_debugfs_create_endpoint_files(struct dwc3_ep *dep,
-		struct dentry *parent)
+void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
 {
+	struct dentry		*dir;
 	int			i;
 
+	dir = debugfs_create_dir(dep->name, dep->dwc->debug_root);
 	for (i = 0; i < ARRAY_SIZE(dwc3_ep_file_map); i++) {
 		const struct file_operations *fops = dwc3_ep_file_map[i].fops;
 		const char *name = dwc3_ep_file_map[i].name;
 
-		debugfs_create_file(name, 0444, parent, dep, fops);
+		debugfs_create_file(name, 0444, dir, dep, fops);
 	}
 }
 
-void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
+void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep)
 {
-	struct dentry		*dir;
-	struct dentry		*root;
-
-	root = debugfs_lookup(dev_name(dep->dwc->dev), usb_debug_root);
-	dir = debugfs_create_dir(dep->name, root);
-	dwc3_debugfs_create_endpoint_files(dep, dir);
+	debugfs_lookup_and_remove(dep->name, dep->dwc->debug_root);
 }
 
 void dwc3_debugfs_init(struct dwc3 *dwc)
@@ -911,6 +907,7 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
 	dwc->regset->base = dwc->regs - DWC3_GLOBALS_REGS_START;
 
 	root = debugfs_create_dir(dev_name(dwc->dev), usb_debug_root);
+	dwc->debug_root = root;
 	debugfs_create_regset32("regdump", 0444, root, dwc->regset);
 	debugfs_create_file("lsp_dump", 0644, root, dwc, &dwc3_lsp_fops);
 
@@ -929,6 +926,6 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
 
 void dwc3_debugfs_exit(struct dwc3 *dwc)
 {
-	debugfs_remove(debugfs_lookup(dev_name(dwc->dev), usb_debug_root));
+	debugfs_lookup_and_remove(dev_name(dwc->dev), usb_debug_root);
 	kfree(dwc->regset);
 }
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 89dcfac01235f..3c63fa97a6800 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3194,9 +3194,7 @@ static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
 			list_del(&dep->endpoint.ep_list);
 		}
 
-		debugfs_remove_recursive(debugfs_lookup(dep->name,
-				debugfs_lookup(dev_name(dep->dwc->dev),
-					       usb_debug_root)));
+		dwc3_debugfs_remove_endpoint_dir(dep);
 		kfree(dep);
 	}
 }
-- 
2.39.2