This is a note to let you know that I've just added the patch titled
USB: usb-skeleton: fix NULL-deref on disconnect
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 bed5ef230943863b9abf5eae226a20fad9a8ff71 Mon Sep 17 00:00:00 2001
From: Johan Hovold johan@kernel.org Date: Wed, 9 Oct 2019 19:09:42 +0200 Subject: USB: usb-skeleton: fix NULL-deref on disconnect
The driver was using its struct usb_interface pointer as an inverted disconnected flag and was setting it to NULL before making sure all completion handlers had run. This could lead to NULL-pointer dereferences in the dev_err() statements in the completion handlers which relies on said pointer.
Fix this by using a dedicated disconnected flag.
Note that this is also addresses a NULL-pointer dereference at release() and a struct usb_interface reference leak introduced by a recent runtime PM fix, which depends on and should have been submitted together with this patch.
Fixes: 4212cd74ca6f ("USB: usb-skeleton.c: remove err() usage") Fixes: 5c290a5e42c3 ("USB: usb-skeleton: fix runtime PM after driver unbind") Cc: stable stable@vger.kernel.org Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20191009170944.30057-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/usb-skeleton.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c index 8001d6384c73..c2843fcfa52d 100644 --- a/drivers/usb/usb-skeleton.c +++ b/drivers/usb/usb-skeleton.c @@ -61,6 +61,7 @@ struct usb_skel { spinlock_t err_lock; /* lock for errors */ struct kref kref; struct mutex io_mutex; /* synchronize I/O with disconnect */ + unsigned long disconnected:1; wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */ }; #define to_skel_dev(d) container_of(d, struct usb_skel, kref) @@ -238,7 +239,7 @@ static ssize_t skel_read(struct file *file, char *buffer, size_t count, if (rv < 0) return rv;
- if (!dev->interface) { /* disconnect() was called */ + if (dev->disconnected) { /* disconnect() was called */ rv = -ENODEV; goto exit; } @@ -420,7 +421,7 @@ static ssize_t skel_write(struct file *file, const char *user_buffer,
/* this lock makes sure we don't submit URBs to gone devices */ mutex_lock(&dev->io_mutex); - if (!dev->interface) { /* disconnect() was called */ + if (dev->disconnected) { /* disconnect() was called */ mutex_unlock(&dev->io_mutex); retval = -ENODEV; goto error; @@ -571,7 +572,7 @@ static void skel_disconnect(struct usb_interface *interface)
/* prevent more I/O from starting */ mutex_lock(&dev->io_mutex); - dev->interface = NULL; + dev->disconnected = 1; mutex_unlock(&dev->io_mutex);
usb_kill_anchored_urbs(&dev->submitted);