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 631202ab1a6a59f13ae7268b11f76057ee9f0ca1 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@xxxxxxxxx>
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.
Cc: <stable@xxxxxxxxxxxxxxx> # 3.15+
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers/jr3_pci.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/staging/comedi/drivers/jr3_pci.c b/drivers/staging/comedi/drivers/jr3_pci.c
index 70390de66e0e..25909a936e7c 100644
--- a/drivers/staging/comedi/drivers/jr3_pci.c
+++ b/drivers/staging/comedi/drivers/jr3_pci.c
@@ -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