Commit 45292be0 authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
Browse files

staging: comedi: jr3_pci: fix possible null pointer dereference 



For some reason, the driver does not consider allocation of the
subdevice private data to be a fatal error when attaching the COMEDI
device.  It tests the subdevice private data pointer for validity at
certain points, but omits some crucial tests.  In particular,
`jr3_pci_auto_attach()` calls `jr3_pci_alloc_spriv()` to allocate and
initialize the subdevice private data, but the same function
subsequently dereferences the pointer to access the `next_time_min` and
`next_time_max` members without checking it first.  The other missing
test is in the timer expiry routine `jr3_pci_poll_dev()`, but it will
crash before it gets that far.

Fix the bug by returning `-ENOMEM` from `jr3_pci_auto_attach()` as soon
as one of the calls to `jr3_pci_alloc_spriv()` returns `NULL`.  The
COMEDI core will subsequently call `jr3_pci_detach()` to clean up.

Cc: <stable@vger.kernel.org> # 3.15+
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 15c012d5

drivers/staging/comedi/drivers/jr3_pci.c

+6 −5
Original line number Diff line number Diff line
@@ -727,12 +727,13 @@ static int jr3_pci_auto_attach(struct comedi_device *dev, 
		s->insn_read	= jr3_pci_ai_insn_read;



		spriv = jr3_pci_alloc_spriv(dev, s);

		if (spriv) {

		if (!spriv)

			return -ENOMEM;



		/* Channel specific range and maxdata */

		s->range_table_list	= spriv->range_table_list;

		s->maxdata_list		= spriv->maxdata_list;

	}

	}



	/* Reset DSP card */

	writel(0, &devpriv->iobase->channel[0].reset);