| Message ID | 20210723155928.210019-1-mdevaev@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] usb: gadget: f_hid: fixed NULL pointer dereference | expand |
On Fri, Jul 23, 2021 at 06:59:30PM +0300, Maxim Devaev wrote: > From: Phil Elwell <phil@raspberrypi.com> > > Disconnecting and reconnecting the USB cable can lead to crashes > and a variety of kernel log spam. > > The problem was found and reproduced on the Raspberry Pi [1] > and the original fix was created in Raspberry's own fork [2]. > > Signed-off-by: Maxim Devaev <mdevaev@gmail.com> > Signed-off-by: Phil Elwell <phil@raspberrypi.com> > Link: https://github.com/raspberrypi/linux/issues/3870 [1] > Link: https://github.com/raspberrypi/linux/commit/a6e47d5f4efbd2ea6a0b6565cd2f9b7bb217ded5 [2] > --- > drivers/usb/gadget/function/f_hid.c | 26 ++++++++++++++++++++------ > 1 file changed, 20 insertions(+), 6 deletions(-) > > diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c > index 02683ac07..08e73e812 100644 > --- a/drivers/usb/gadget/function/f_hid.c > +++ b/drivers/usb/gadget/function/f_hid.c > @@ -338,6 +338,11 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, > > spin_lock_irqsave(&hidg->write_spinlock, flags); > > + if (!hidg->req) { > + spin_unlock_irqrestore(&hidg->write_spinlock, flags); > + return -ESHUTDOWN; > + } > + > #define WRITE_COND (!hidg->write_pending) > try_again: > /* write queue */ > @@ -358,8 +363,14 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, > count = min_t(unsigned, count, hidg->report_length); > > spin_unlock_irqrestore(&hidg->write_spinlock, flags); > - status = copy_from_user(req->buf, buffer, count); > > + if (!req) { > + ERROR(hidg->func.config->cdev, "hidg->req is NULL\n"); > + status = -ESHUTDOWN; > + goto release_write_pending; > + } > + > + status = copy_from_user(req->buf, buffer, count); > if (status != 0) { > ERROR(hidg->func.config->cdev, > "copy_from_user error\n"); > @@ -387,14 +398,17 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, > > spin_unlock_irqrestore(&hidg->write_spinlock, flags); > > + if (!hidg->in_ep->enabled) { > + ERROR(hidg->func.config->cdev, "in_ep is disabled\n"); > + status = -ESHUTDOWN; > + goto release_write_pending; What prevents "enabled" from changing right after you test this? You do not have the lock held so could it change then? > + } > + > status = usb_ep_queue(hidg->in_ep, req, GFP_ATOMIC); > - if (status < 0) { > - ERROR(hidg->func.config->cdev, > - "usb_ep_queue error on int endpoint %zd\n", status); > + if (status < 0) > goto release_write_pending; No error message if queueing up failed? thanks, greg k-h
> > + if (!hidg->in_ep->enabled) { > > + ERROR(hidg->func.config->cdev, "in_ep is disabled\n"); > > + status = -ESHUTDOWN; > > + goto release_write_pending; > > What prevents "enabled" from changing right after you test this? You do > not have the lock held so could it change then? Inside usb_ep_queue() a similar check is used without blocking. I suppose this is how it should be. Here it's necessary for the error message. > > + } > > + > > status = usb_ep_queue(hidg->in_ep, req, GFP_ATOMIC); > > - if (status < 0) { > > - ERROR(hidg->func.config->cdev, > > - "usb_ep_queue error on int endpoint %zd\n", status); > > + if (status < 0) > > goto release_write_pending; > > No error message if queueing up failed? Yes. For each write from userspace, this generates one message. This can lead to a huge spam in the log.
diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c index 02683ac07..08e73e812 100644 --- a/drivers/usb/gadget/function/f_hid.c +++ b/drivers/usb/gadget/function/f_hid.c @@ -338,6 +338,11 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, spin_lock_irqsave(&hidg->write_spinlock, flags); + if (!hidg->req) { + spin_unlock_irqrestore(&hidg->write_spinlock, flags); + return -ESHUTDOWN; + } + #define WRITE_COND (!hidg->write_pending) try_again: /* write queue */ @@ -358,8 +363,14 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, count = min_t(unsigned, count, hidg->report_length); spin_unlock_irqrestore(&hidg->write_spinlock, flags); - status = copy_from_user(req->buf, buffer, count); + if (!req) { + ERROR(hidg->func.config->cdev, "hidg->req is NULL\n"); + status = -ESHUTDOWN; + goto release_write_pending; + } + + status = copy_from_user(req->buf, buffer, count); if (status != 0) { ERROR(hidg->func.config->cdev, "copy_from_user error\n"); @@ -387,14 +398,17 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, spin_unlock_irqrestore(&hidg->write_spinlock, flags); + if (!hidg->in_ep->enabled) { + ERROR(hidg->func.config->cdev, "in_ep is disabled\n"); + status = -ESHUTDOWN; + goto release_write_pending; + } + status = usb_ep_queue(hidg->in_ep, req, GFP_ATOMIC); - if (status < 0) { - ERROR(hidg->func.config->cdev, - "usb_ep_queue error on int endpoint %zd\n", status); + if (status < 0) goto release_write_pending; - } else { + else status = count; - } return status; release_write_pending: