From 7fc6659b19a26fb2c10e10e56af0f5c3d766a378 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Fri, 17 Feb 2017 11:09:08 +0000 Subject: [PATCH] staging: comedi: jr3_pci: fix possible null pointer dereference commit 45292be0b3db0b7f8286683b376e2d9f949d11f9 upstream. 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. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- 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 b87192e0f9aa..6c0e9dda571a 100644 --- a/drivers/staging/comedi/drivers/jr3_pci.c +++ b/drivers/staging/comedi/drivers/jr3_pci.c @@ -726,11 +726,12 @@ 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 */ -- 2.20.1