This is a note to let you know that I've just added the patch titled
staging: comedi: ni_usb6501: Fix possible double-free of ->usb_rx_buf
to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-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 af4b54a2e5ba18259ff9aac445bf546dd60d037e Mon Sep 17 00:00:00 2001
From: Ian Abbott abbotti@mev.co.uk Date: Mon, 15 Apr 2019 12:43:02 +0100 Subject: 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 --- drivers/staging/comedi/drivers/ni_usb6501.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/staging/comedi/drivers/ni_usb6501.c b/drivers/staging/comedi/drivers/ni_usb6501.c index ed5e42655821..1bb1cb651349 100644 --- a/drivers/staging/comedi/drivers/ni_usb6501.c +++ b/drivers/staging/comedi/drivers/ni_usb6501.c @@ -463,10 +463,8 @@ static int ni6501_alloc_usb_buffers(struct comedi_device *dev)
size = usb_endpoint_maxp(devpriv->ep_tx); devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL); - if (!devpriv->usb_tx_buf) { - kfree(devpriv->usb_rx_buf); + if (!devpriv->usb_tx_buf) return -ENOMEM; - }
return 0; }