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@xxxxxxxxx>
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@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
--
2.21.0
