FAILED: patch "[PATCH] net: hso: fix null-ptr-deref during tty device unregistration" failed to apply to 4.14-stable tree

PATCH [email protected] 2 participants 3 messages Apr 10, 2021 – Apr 24, 2021

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[email protected]

author maintainer

2021-04-10 14:01 UTC #0 lore raw

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8a12f8836145ffe37e9c8733dce18c22fb668b66 Mon Sep 17 00:00:00 2001
From: Anirudh Rayabharam <[email protected]>
Date: Wed, 7 Apr 2021 22:57:22 +0530
Subject: [PATCH] net: hso: fix null-ptr-deref during tty device unregistration

Multiple ttys try to claim the same the minor number causing a double unregistration of the same device. The first unregistration succeeds but the next one results in a null-ptr-deref.

The get_free_serial_index() function returns an available minor number but doesn't assign it immediately. The assignment is done by the caller later. But before this assignment, calls to get_free_serial_index() would return the same minor number.

Fix this by modifying get_free_serial_index to assign the minor number immediately after one is found to be and rename it to obtain_minor() to better reflect what it does. Similary, rename set_serial_by_index() to release_minor() and modify it to free up the minor number of the given hso_serial. Every obtain_minor() should have corresponding release_minor() call.

Fixes 72dc1c096c705 ("HSO: add option hso driver")

Reported-by [email protected]

Tested-by [email protected]

Reviewed-by Greg Kroah-Hartman <[email protected]>

Signed-off-by Anirudh Rayabharam <[email protected]>

Signed-off-by David S. Miller <[email protected]>

drivers/net/usb/hso.c +12 ~~-21~~

index 31d51346786a..9bc58e64b5b7 100644
@@ -611,7 +611,7 @@ static struct hso_serial *get_serial_by_index(unsigned index)
 	return serial;
 }
 
-static int get_free_serial_index(void)
+static int obtain_minor(struct hso_serial *serial)
 {
 	int index;
 	unsigned long flags;

@@ -619,8 +619,10 @@ static int get_free_serial_index(void)
 	spin_lock_irqsave(&serial_table_lock, flags);
 	for (index = 0; index < HSO_SERIAL_TTY_MINORS; index++) {
 		if (serial_table[index] == NULL) {
+			serial_table[index] = serial->parent;
+			serial->minor = index;
 			spin_unlock_irqrestore(&serial_table_lock, flags);
-			return index;
+			return 0;
 		}
 	}
 	spin_unlock_irqrestore(&serial_table_lock, flags);

@@ -629,15 +631,12 @@ static int get_free_serial_index(void)
 	return -1;
 }
 
-static void set_serial_by_index(unsigned index, struct hso_serial *serial)
+static void release_minor(struct hso_serial *serial)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&serial_table_lock, flags);
-	if (serial)
-		serial_table[index] = serial->parent;
-	else
-		serial_table[index] = NULL;
+	serial_table[serial->minor] = NULL;
 	spin_unlock_irqrestore(&serial_table_lock, flags);
 }

@@ -2230,6 +2229,7 @@ static int hso_stop_serial_device(struct hso_device *hso_dev)
 static void hso_serial_tty_unregister(struct hso_serial *serial)
 {
 	tty_unregister_device(tty_drv, serial->minor);
+	release_minor(serial);
 }
 
 static void hso_serial_common_free(struct hso_serial *serial)

@@ -2253,24 +2253,22 @@ static void hso_serial_common_free(struct hso_serial *serial)
 static int hso_serial_common_create(struct hso_serial *serial, int num_urbs,
 				    int rx_size, int tx_size)
 {
-	int minor;
 	int i;
 
 	tty_port_init(&serial->port);
 
-	minor = get_free_serial_index();
-	if (minor < 0)
+	if (obtain_minor(serial))
 		goto exit2;
 
 	/* register our minor number */
 	serial->parent->dev = tty_port_register_device_attr(&serial->port,
-			tty_drv, minor, &serial->parent->interface->dev,
+			tty_drv, serial->minor, &serial->parent->interface->dev,
 			serial->parent, hso_serial_dev_groups);
-	if (IS_ERR(serial->parent->dev))
+	if (IS_ERR(serial->parent->dev)) {
+		release_minor(serial);
 		goto exit2;
+	}
 
-	/* fill in specific data for later use */
-	serial->minor = minor;
 	serial->magic = HSO_SERIAL_MAGIC;
 	spin_lock_init(&serial->serial_lock);
 	serial->num_rx_urbs = num_urbs;

@@ -2667,9 +2665,6 @@ static struct hso_device *hso_create_bulk_serial_device(
 
 	serial->write_data = hso_std_serial_write_data;
 
-	/* and record this serial */
-	set_serial_by_index(serial->minor, serial);
-
 	/* setup the proc dirs and files if needed */
 	hso_log_port(hso_dev);

@@ -2726,9 +2721,6 @@ struct hso_device *hso_create_mux_serial_device(struct usb_interface *interface,
 	serial->shared_int->ref_count++;
 	mutex_unlock(&serial->shared_int->shared_int_lock);
 
-	/* and record this serial */
-	set_serial_by_index(serial->minor, serial);
-
 	/* setup the proc dirs and files if needed */
 	hso_log_port(hso_dev);

@@ -3113,7 +3105,6 @@ static void hso_free_interface(struct usb_interface *interface)
 			cancel_work_sync(&serial_table[i]->async_get_intf);
 			hso_serial_tty_unregister(serial);
 			kref_put(&serial_table[i]->ref, hso_serial_ref_free);
-			set_serial_by_index(i, NULL);
 		}
 	}

Sudip Mukherjee

Tested-by [email protected] Reviewed-by Greg Kroah-Hartman

2021-04-23 19:08 UTC #1 lore raw

Hi Greg,

Quoted 5 lines · On Sat, Apr 10, 2021 at 04:01:43PM +0200, [email protected] wrote:

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Here is the backport. Will also apply for 4.9-stable and 4.4-stable.

--
Regards
Sudip

From 69dd8d3a3061aa50deec6aa17f9c8da618dd6c21 Mon Sep 17 00:00:00 2001
From: Anirudh Rayabharam <[email protected]>
Date: Wed, 7 Apr 2021 22:57:22 +0530
Subject: [PATCH] net: hso: fix null-ptr-deref during tty device unregistration

commit 8a12f8836145ffe37e9c8733dce18c22fb668b66 upstream

Multiple ttys try to claim the same the minor number causing a double unregistration of the same device. The first unregistration succeeds but the next one results in a null-ptr-deref.

Fixes 72dc1c096c705 ("HSO: add option hso driver")

Reported-by [email protected]

Tested-by [email protected]

Reviewed-by Greg Kroah-Hartman <[email protected]>

Signed-off-by Anirudh Rayabharam <[email protected]>

Signed-off-by David S. Miller <[email protected]>

[sudip: adjust context]

Signed-off-by Sudip Mukherjee <[email protected]>

---
 drivers/net/usb/hso.c | 33 ++++++++++++---------------------
 1 file changed, 12 insertions(+), 21 deletions(-)

drivers/net/usb/hso.c +12 ~~-21~~

index 0e3d13e192e3..16f81fafde2a 100644
@@ -626,7 +626,7 @@ static struct hso_serial *get_serial_by_index(unsigned index)
 	return serial;
 }
 
-static int get_free_serial_index(void)
+static int obtain_minor(struct hso_serial *serial)
 {
 	int index;
 	unsigned long flags;

@@ -634,8 +634,10 @@ static int get_free_serial_index(void)
 	spin_lock_irqsave(&serial_table_lock, flags);
 	for (index = 0; index < HSO_SERIAL_TTY_MINORS; index++) {
 		if (serial_table[index] == NULL) {
+			serial_table[index] = serial->parent;
+			serial->minor = index;
 			spin_unlock_irqrestore(&serial_table_lock, flags);
-			return index;
+			return 0;
 		}
 	}
 	spin_unlock_irqrestore(&serial_table_lock, flags);

@@ -644,15 +646,12 @@ static int get_free_serial_index(void)
 	return -1;
 }
 
-static void set_serial_by_index(unsigned index, struct hso_serial *serial)
+static void release_minor(struct hso_serial *serial)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&serial_table_lock, flags);
-	if (serial)
-		serial_table[index] = serial->parent;
-	else
-		serial_table[index] = NULL;
+	serial_table[serial->minor] = NULL;
 	spin_unlock_irqrestore(&serial_table_lock, flags);
 }

@@ -2241,6 +2240,7 @@ static int hso_stop_serial_device(struct hso_device *hso_dev)
 static void hso_serial_tty_unregister(struct hso_serial *serial)
 {
 	tty_unregister_device(tty_drv, serial->minor);
+	release_minor(serial);
 }
 
 static void hso_serial_common_free(struct hso_serial *serial)

@@ -2265,25 +2265,23 @@ static int hso_serial_common_create(struct hso_serial *serial, int num_urbs,
 				    int rx_size, int tx_size)
 {
 	struct device *dev;
-	int minor;
 	int i;
 
 	tty_port_init(&serial->port);
 
-	minor = get_free_serial_index();
-	if (minor < 0)
+	if (obtain_minor(serial))
 		goto exit2;
 
 	/* register our minor number */
 	serial->parent->dev = tty_port_register_device_attr(&serial->port,
-			tty_drv, minor, &serial->parent->interface->dev,
+			tty_drv, serial->minor, &serial->parent->interface->dev,
 			serial->parent, hso_serial_dev_groups);
-	if (IS_ERR(serial->parent->dev))
+	if (IS_ERR(serial->parent->dev)) {
+		release_minor(serial);
 		goto exit2;
+	}
 	dev = serial->parent->dev;
 
-	/* fill in specific data for later use */
-	serial->minor = minor;
 	serial->magic = HSO_SERIAL_MAGIC;
 	spin_lock_init(&serial->serial_lock);
 	serial->num_rx_urbs = num_urbs;

@@ -2676,9 +2674,6 @@ static struct hso_device *hso_create_bulk_serial_device(
 
 	serial->write_data = hso_std_serial_write_data;
 
-	/* and record this serial */
-	set_serial_by_index(serial->minor, serial);
-
 	/* setup the proc dirs and files if needed */
 	hso_log_port(hso_dev);

@@ -2735,9 +2730,6 @@ struct hso_device *hso_create_mux_serial_device(struct usb_interface *interface,
 	serial->shared_int->ref_count++;
 	mutex_unlock(&serial->shared_int->shared_int_lock);
 
-	/* and record this serial */
-	set_serial_by_index(serial->minor, serial);
-
 	/* setup the proc dirs and files if needed */
 	hso_log_port(hso_dev);

@@ -3122,7 +3114,6 @@ static void hso_free_interface(struct usb_interface *interface)
 			cancel_work_sync(&serial_table[i]->async_get_intf);
 			hso_serial_tty_unregister(serial);
 			kref_put(&serial_table[i]->ref, hso_serial_ref_free);
-			set_serial_by_index(i, NULL);
 		}
 	}

Signature · 1 line

2.30.2

Greg KH

author maintainer

2021-04-24 14:46 UTC #2 lore raw

Quoted 10 lines · Sudip Mukherjee

Hi Greg,
Quoted 5 lines · On Sat, Apr 10, 2021 at 04:01:43PM +0200, [email protected] wrote:
The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
Here is the backport. Will also apply for 4.9-stable and 4.4-stable.

Thanks, now queued up.

greg k-h