* [PATCH 1/2] USB: adutux: fix use-after-free on disconnect
@ 2019-09-25 9:29 Johan Hovold
2019-09-25 9:29 ` [PATCH 2/2] USB: adutux: fix NULL-derefs " Johan Hovold
0 siblings, 1 reply; 2+ messages in thread
From: Johan Hovold @ 2019-09-25 9:29 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-usb, Johan Hovold, stable, syzbot+0243cb250a51eeefb8cc
The driver was clearing its struct usb_device pointer, which it used as
an inverted disconnected flag, before deregistering the character device
and without serialising against racing release().
This could lead to a use-after-free if a racing release() callback
observes the cleared pointer and frees the driver data before
disconnect() is finished with it.
This could also lead to NULL-pointer dereferences in a racing open().
Fixes: f08812d5eb8f ("USB: FIx locks and urb->status in adutux (updated)")
Cc: stable <stable@vger.kernel.org> # 2.6.24
Reported-by: syzbot+0243cb250a51eeefb8cc@syzkaller.appspotmail.com
Tested-by: syzbot+0243cb250a51eeefb8cc@syzkaller.appspotmail.com
Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/usb/misc/adutux.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/misc/adutux.c b/drivers/usb/misc/adutux.c
index 344d523b0502..bcc138990e2f 100644
--- a/drivers/usb/misc/adutux.c
+++ b/drivers/usb/misc/adutux.c
@@ -762,14 +762,15 @@ static void adu_disconnect(struct usb_interface *interface)
dev = usb_get_intfdata(interface);
- mutex_lock(&dev->mtx); /* not interruptible */
- dev->udev = NULL; /* poison */
usb_deregister_dev(interface, &adu_class);
- mutex_unlock(&dev->mtx);
mutex_lock(&adutux_mutex);
usb_set_intfdata(interface, NULL);
+ mutex_lock(&dev->mtx); /* not interruptible */
+ dev->udev = NULL; /* poison */
+ mutex_unlock(&dev->mtx);
+
/* if the device is not opened, then we clean up right now */
if (!dev->open_count)
adu_delete(dev);
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH 2/2] USB: adutux: fix NULL-derefs on disconnect
2019-09-25 9:29 [PATCH 1/2] USB: adutux: fix use-after-free on disconnect Johan Hovold
@ 2019-09-25 9:29 ` Johan Hovold
0 siblings, 0 replies; 2+ messages in thread
From: Johan Hovold @ 2019-09-25 9:29 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: linux-usb, Johan Hovold, stable
The driver was using its struct usb_device pointer as an inverted
disconnected flag, but was setting it to NULL before making sure all
completion handlers had run. This could lead to a NULL-pointer
dereference in a number of dev_dbg statements in the completion handlers
which relies on said pointer.
The pointer was also dereferenced unconditionally in a dev_dbg statement
release() something which would lead to a NULL-deref whenever a device
was disconnected before the final character-device close if debugging
was enabled.
Fix this by unconditionally stopping all I/O and preventing
resubmissions by poisoning the interrupt URBs at disconnect and using a
dedicated disconnected flag.
This also makes sure that all I/O has completed by the time the
disconnect callback returns.
Fixes: 1ef37c6047fe ("USB: adutux: remove custom debug macro and module parameter")
Fixes: 66d4bc30d128 ("USB: adutux: remove custom debug macro")
Cc: stable <stable@vger.kernel.org> # 3.12
Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/usb/misc/adutux.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/misc/adutux.c b/drivers/usb/misc/adutux.c
index bcc138990e2f..f9efec719359 100644
--- a/drivers/usb/misc/adutux.c
+++ b/drivers/usb/misc/adutux.c
@@ -75,6 +75,7 @@ struct adu_device {
char serial_number[8];
int open_count; /* number of times this port has been opened */
+ unsigned long disconnected:1;
char *read_buffer_primary;
int read_buffer_length;
@@ -116,7 +117,7 @@ static void adu_abort_transfers(struct adu_device *dev)
{
unsigned long flags;
- if (dev->udev == NULL)
+ if (dev->disconnected)
return;
/* shutdown transfer */
@@ -243,7 +244,7 @@ static int adu_open(struct inode *inode, struct file *file)
}
dev = usb_get_intfdata(interface);
- if (!dev || !dev->udev) {
+ if (!dev) {
retval = -ENODEV;
goto exit_no_device;
}
@@ -326,7 +327,7 @@ static int adu_release(struct inode *inode, struct file *file)
}
adu_release_internal(dev);
- if (dev->udev == NULL) {
+ if (dev->disconnected) {
/* the device was unplugged before the file was released */
if (!dev->open_count) /* ... and we're the last user */
adu_delete(dev);
@@ -354,7 +355,7 @@ static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
return -ERESTARTSYS;
/* verify that the device wasn't unplugged */
- if (dev->udev == NULL) {
+ if (dev->disconnected) {
retval = -ENODEV;
pr_err("No device or device unplugged %d\n", retval);
goto exit;
@@ -518,7 +519,7 @@ static ssize_t adu_write(struct file *file, const __user char *buffer,
goto exit_nolock;
/* verify that the device wasn't unplugged */
- if (dev->udev == NULL) {
+ if (dev->disconnected) {
retval = -ENODEV;
pr_err("No device or device unplugged %d\n", retval);
goto exit;
@@ -764,11 +765,14 @@ static void adu_disconnect(struct usb_interface *interface)
usb_deregister_dev(interface, &adu_class);
+ usb_poison_urb(dev->interrupt_in_urb);
+ usb_poison_urb(dev->interrupt_out_urb);
+
mutex_lock(&adutux_mutex);
usb_set_intfdata(interface, NULL);
mutex_lock(&dev->mtx); /* not interruptible */
- dev->udev = NULL; /* poison */
+ dev->disconnected = 1;
mutex_unlock(&dev->mtx);
/* if the device is not opened, then we clean up right now */
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
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