patch "staging: comedi: jr3_pci: fix possible null pointer dereference" added to staging-testing

This is a note to let you know that I've just added the patch titled

staging: comedi: jr3_pci: fix possible null pointer dereference

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-testing 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 be merged to the staging-next branch sometime soon, after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.

From: Ian Abbott <[email protected]>
Date: Fri, 17 Feb 2017 11:09:08 +0000
Subject: 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.

---
 drivers/staging/comedi/drivers/jr3_pci.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

index 70390de66e0e..25909a936e7c 100644
@@ -727,11 +727,12 @@ 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) {
-			/* Channel specific range and maxdata */
-			s->range_table_list	= spriv->range_table_list;
-			s->maxdata_list		= spriv->maxdata_list;
-		}
+		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 */

2.11.1