From: Johan Hovold Date: Wed, 9 Oct 2019 10:48:41 +0000 (+0200) Subject: USB: iowarrior: fix use-after-free on disconnect X-Git-Url: http://git.osdn.net/view?p=sagit-ice-cold%2Fkernel_xiaomi_msm8998.git;a=commitdiff_plain;h=f723d7ea08e2c69ac9ecd87828c650745270fb98 USB: iowarrior: fix use-after-free on disconnect commit edc4746f253d907d048de680a621e121517f484b upstream. A recent fix addressing a deadlock on disconnect introduced a new bug by moving the present flag out of the critical section protected by the driver-data mutex. This could lead to a racing release() freeing the driver data before disconnect() is done with it. Due to insufficient locking a related use-after-free could be triggered also before the above mentioned commit. Specifically, the driver needs to hold the driver-data mutex also while checking the opened flag at disconnect(). Fixes: c468a8aa790e ("usb: iowarrior: fix deadlock on disconnect") Fixes: 946b960d13c1 ("USB: add driver for iowarrior devices.") Cc: stable # 2.6.21 Reported-by: syzbot+0761012cebf7bdb38137@syzkaller.appspotmail.com Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20191009104846.5925-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c index 836fb65c3c72..4af9279f2cf0 100644 --- a/drivers/usb/misc/iowarrior.c +++ b/drivers/usb/misc/iowarrior.c @@ -898,8 +898,6 @@ static void iowarrior_disconnect(struct usb_interface *interface) dev = usb_get_intfdata(interface); mutex_lock(&iowarrior_open_disc_lock); usb_set_intfdata(interface, NULL); - /* prevent device read, write and ioctl */ - dev->present = 0; minor = dev->minor; mutex_unlock(&iowarrior_open_disc_lock); @@ -910,8 +908,7 @@ static void iowarrior_disconnect(struct usb_interface *interface) mutex_lock(&dev->mutex); /* prevent device read, write and ioctl */ - - mutex_unlock(&dev->mutex); + dev->present = 0; if (dev->opened) { /* There is a process that holds a filedescriptor to the device , @@ -921,8 +918,10 @@ static void iowarrior_disconnect(struct usb_interface *interface) usb_kill_urb(dev->int_in_urb); wake_up_interruptible(&dev->read_wait); wake_up_interruptible(&dev->write_wait); + mutex_unlock(&dev->mutex); } else { /* no process is using the device, cleanup now */ + mutex_unlock(&dev->mutex); iowarrior_delete(dev); }