staging: comedi: ni_usb6501: Fix possible double-free of ->usb_rx_buf
`ni6501_alloc_usb_buffers()` is called from `ni6501_auto_attach()` to allocate RX and TX buffers for USB transfers. It allocates `devpriv->usb_rx_buf` followed by `devpriv->usb_tx_buf`. If the allocation of `devpriv->usb_tx_buf` fails, it frees `devpriv->usb_rx_buf`, leaving the pointer set dangling, and returns an error. Later, `ni6501_detach()` will be called from the core comedi module code to clean up. `ni6501_detach()` also frees both `devpriv->usb_rx_buf` and `devpriv->usb_tx_buf`, but `devpriv->usb_rx_buf` may have already beed freed, leading to a double-free error. Fix it bu removing the call to `kfree(devpriv->usb_rx_buf)` from `ni6501_alloc_usb_buffers()`, relying on `ni6501_detach()` to free the memory. Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -463,10 +463,8 @@ static int ni6501_alloc_usb_buffers(struct comedi_device *dev)
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size = usb_endpoint_maxp(devpriv->ep_tx);
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size = usb_endpoint_maxp(devpriv->ep_tx);
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devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL);
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devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL);
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if (!devpriv->usb_tx_buf) {
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if (!devpriv->usb_tx_buf)
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kfree(devpriv->usb_rx_buf);
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return -ENOMEM;
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return -ENOMEM;
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}
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return 0;
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return 0;
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}
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}
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