On Wed, Jul 14, 2021 at 3:36 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > > On Wed, Jul 14, 2021 at 03:15:32PM +0800, Dongliang Mu wrote: > > The current error handling code of hso_create_net_device is > > hso_free_net_device, no matter which errors lead to. For example, > > WARNING in hso_free_net_device [1]. > > > > Fix this by refactoring the error handling code of > > hso_create_net_device by handling different errors by different code. > > > > [1] https://syzkaller.appspot.com/bug?id=66eff8d49af1b28370ad342787413e35bbe76efe > > > > Reported-by: syzbot+44d53c7255bb1aea22d2@xxxxxxxxxxxxxxxxxxxxxxxxx > > Fixes: 5fcfb6d0bfcd ("hso: fix bailout in error case of probe") > > Signed-off-by: Dongliang Mu <mudongliangabcd@xxxxxxxxx> > > --- > > drivers/net/usb/hso.c | 37 +++++++++++++++++++++++++++---------- > > 1 file changed, 27 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c > > index 54ef8492ca01..90fa4d9fa119 100644 > > --- a/drivers/net/usb/hso.c > > +++ b/drivers/net/usb/hso.c > > @@ -2495,7 +2495,9 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface, > > hso_net_init); > > if (!net) { > > dev_err(&interface->dev, "Unable to create ethernet device\n"); > > - goto exit; > > + kfree(hso_dev); > > + usb_free_urb(hso_net->mux_bulk_tx_urb); > > Obviously this wasn't intentional. This is a copy-paste error. I am sorry. :( > > > + return NULL; > > But use gotos here. OK, I will change it in version v2. > > > } > > > > hso_net = netdev_priv(net); > > @@ -2508,13 +2510,13 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface, > > USB_DIR_IN); > > if (!hso_net->in_endp) { > > dev_err(&interface->dev, "Can't find BULK IN endpoint\n"); > > - goto exit; > > + goto err_get_ep; > > This is Come From naming style where it says what failed on the line > before. It's not helpful because we can see what failed. What we need > to know is what the goto does. > > Use Free the Last thing style. Where you just keep track of the most > recent successful allocation and free it. That way you don't free > things which aren't allocated, you don't double free things, you don't > dereference uninitialized variables or error points. Plus it's a very > simple system where when you're reading code you just have to remember > the last thing that was allocated. Every function must clean up after > itself. Every allocation function needs a free function. The goto > names say the variable that is freed. That's a good rule to follow. Will change the patch following this rule. > > goto free_net; > > > } > > hso_net->out_endp = hso_get_ep(interface, USB_ENDPOINT_XFER_BULK, > > USB_DIR_OUT); > > if (!hso_net->out_endp) { > > dev_err(&interface->dev, "Can't find BULK OUT endpoint\n"); > > - goto exit; > > + goto err_get_ep; > > } > > SET_NETDEV_DEV(net, &interface->dev); > > SET_NETDEV_DEVTYPE(net, &hso_type); > > @@ -2523,18 +2525,18 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface, > > for (i = 0; i < MUX_BULK_RX_BUF_COUNT; i++) { > > hso_net->mux_bulk_rx_urb_pool[i] = usb_alloc_urb(0, GFP_KERNEL); > > if (!hso_net->mux_bulk_rx_urb_pool[i]) > > - goto exit; > > + goto err_mux_bulk_rx; > > hso_net->mux_bulk_rx_buf_pool[i] = kzalloc(MUX_BULK_RX_BUF_SIZE, > > GFP_KERNEL); > > if (!hso_net->mux_bulk_rx_buf_pool[i]) > > - goto exit; > > + goto err_mux_bulk_rx; > > In a loop then how Free the last thing style works is that you free > that partial allocation before the goto. And then do a > > while (--i >= 0) { > free_c(); > free_b(); > free_a(); > } > You have told me this rule. But I think the handling of this loop does not need to be such complicated. > But in this case your code is fine and simple enough. No need to be > dogmatic about style so long as the functions are small. Thanks. > > > } > > hso_net->mux_bulk_tx_urb = usb_alloc_urb(0, GFP_KERNEL); > > if (!hso_net->mux_bulk_tx_urb) > > - goto exit; > > + goto err_mux_bulk_tx; > > hso_net->mux_bulk_tx_buf = kzalloc(MUX_BULK_TX_BUF_SIZE, GFP_KERNEL); > > if (!hso_net->mux_bulk_tx_buf) > > - goto exit; > > + goto err_mux_bulk_tx; > > > These gotos are freeing things which haven't been allocated. Which is > harmless in this case but puzzling. I will revise this label in the v2 version. > > > > > add_net_device(hso_dev); > > > > @@ -2542,7 +2544,7 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface, > > result = register_netdev(net); > > if (result) { > > dev_err(&interface->dev, "Failed to register device\n"); > > - goto exit; > > + goto err_register; > > In this case register failed and calling unregister_netdev() will lead > to WARN_ON(1) and a stack trace. > I will revise this label in the v2 version. > > } > > > > hso_log_port(hso_dev); > > @@ -2550,8 +2552,23 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface, > > hso_create_rfkill(hso_dev, interface); > > > > return hso_dev; > > -exit: > > - hso_free_net_device(hso_dev, true); > > + > > +err_register: > > + unregister_netdev(net); > > + remove_net_device(hso_dev); > > +err_mux_bulk_tx: > > + kfree(hso_net->mux_bulk_tx_buf); > > + hso_net->mux_bulk_tx_buf = NULL; > > No need for this. > > > + usb_free_urb(hso_net->mux_bulk_tx_urb); > > +err_mux_bulk_rx: > > + for (i = 0; i < MUX_BULK_RX_BUF_COUNT; i++) { > > + usb_free_urb(hso_net->mux_bulk_rx_urb_pool[i]); > > + kfree(hso_net->mux_bulk_rx_buf_pool[i]); > > + hso_net->mux_bulk_rx_buf_pool[i] = NULL; > > No need. This memory is just going to be freed. > > > + } > > +err_get_ep: > > + free_netdev(net); > > + kfree(hso_dev); > > return NULL; > > } > > regards, > dan carpenter
