This is a note to let you know that I've just added the patch titled
USB: ldusb: fix NULL-derefs on driver unbind
to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From 58ecf131e74620305175a7aa103f81350bb37570 Mon Sep 17 00:00:00 2001
From: Johan Hovold johan@kernel.org Date: Wed, 9 Oct 2019 17:38:46 +0200 Subject: USB: ldusb: fix NULL-derefs on driver unbind
The driver was using its struct usb_interface 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, dev_warn and dev_err statements in the completion handlers which relies on said pointer.
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: 2824bd250f0b ("[PATCH] USB: add ldusb driver") Cc: stable stable@vger.kernel.org # 2.6.13 Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20191009153848.8664-4-johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/misc/ldusb.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/drivers/usb/misc/ldusb.c b/drivers/usb/misc/ldusb.c index 6581774bdfa4..f3108d85e768 100644 --- a/drivers/usb/misc/ldusb.c +++ b/drivers/usb/misc/ldusb.c @@ -153,6 +153,7 @@ MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in struct ld_usb { struct mutex mutex; /* locks this structure */ struct usb_interface *intf; /* save off the usb interface pointer */ + unsigned long disconnected:1;
int open_count; /* number of times this port has been opened */
@@ -192,12 +193,10 @@ static void ld_usb_abort_transfers(struct ld_usb *dev) /* shutdown transfer */ if (dev->interrupt_in_running) { dev->interrupt_in_running = 0; - if (dev->intf) - usb_kill_urb(dev->interrupt_in_urb); + usb_kill_urb(dev->interrupt_in_urb); } if (dev->interrupt_out_busy) - if (dev->intf) - usb_kill_urb(dev->interrupt_out_urb); + usb_kill_urb(dev->interrupt_out_urb); }
/** @@ -205,8 +204,6 @@ static void ld_usb_abort_transfers(struct ld_usb *dev) */ static void ld_usb_delete(struct ld_usb *dev) { - ld_usb_abort_transfers(dev); - /* free data structures */ usb_free_urb(dev->interrupt_in_urb); usb_free_urb(dev->interrupt_out_urb); @@ -263,7 +260,7 @@ static void ld_usb_interrupt_in_callback(struct urb *urb)
resubmit: /* resubmit if we're still running */ - if (dev->interrupt_in_running && !dev->buffer_overflow && dev->intf) { + if (dev->interrupt_in_running && !dev->buffer_overflow) { retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC); if (retval) { dev_err(&dev->intf->dev, @@ -392,7 +389,7 @@ static int ld_usb_release(struct inode *inode, struct file *file) retval = -ENODEV; goto unlock_exit; } - if (dev->intf == NULL) { + if (dev->disconnected) { /* the device was unplugged before the file was released */ mutex_unlock(&dev->mutex); /* unlock here as ld_usb_delete frees dev */ @@ -423,7 +420,7 @@ static __poll_t ld_usb_poll(struct file *file, poll_table *wait)
dev = file->private_data;
- if (!dev->intf) + if (dev->disconnected) return EPOLLERR | EPOLLHUP;
poll_wait(file, &dev->read_wait, wait); @@ -462,7 +459,7 @@ static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count, }
/* verify that the device wasn't unplugged */ - if (dev->intf == NULL) { + if (dev->disconnected) { retval = -ENODEV; printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval); goto unlock_exit; @@ -542,7 +539,7 @@ static ssize_t ld_usb_write(struct file *file, const char __user *buffer, }
/* verify that the device wasn't unplugged */ - if (dev->intf == NULL) { + if (dev->disconnected) { retval = -ENODEV; printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval); goto unlock_exit; @@ -764,6 +761,9 @@ static void ld_usb_disconnect(struct usb_interface *intf) /* give back our minor */ usb_deregister_dev(intf, &ld_usb_class);
+ usb_poison_urb(dev->interrupt_in_urb); + usb_poison_urb(dev->interrupt_out_urb); + mutex_lock(&dev->mutex);
/* if the device is not opened, then we clean up right now */ @@ -771,7 +771,7 @@ static void ld_usb_disconnect(struct usb_interface *intf) mutex_unlock(&dev->mutex); ld_usb_delete(dev); } else { - dev->intf = NULL; + dev->disconnected = 1; /* wake up pollers */ wake_up_interruptible_all(&dev->read_wait); wake_up_interruptible_all(&dev->write_wait);