From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Date: Thu, 09 Jul 2020 10:29:36 +0000 Subject: [PATCH] staging: comedi: verify array index is correct before using it Message-Id: <20200709102936.GA20875@mwanda> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ian Abbott , H Hartley Sweeten Cc: devel@driverdev.osuosl.org, Greg Kroah-Hartman , kernel-janitors@vger.kernel.org This code reads from the array before verifying that "trig" is a valid index. If the index is wildly out of bounds then reading from an invalid address could lead to an Oops. Fixes: a8c66b684efa ("staging: comedi: addi_apci_1500: rewrite the subdevice support functions") Signed-off-by: Dan Carpenter --- drivers/staging/comedi/drivers/addi_apci_1500.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/staging/comedi/drivers/addi_apci_1500.c b/drivers/staging/comedi/drivers/addi_apci_1500.c index 45ad4ba92f94..689acd69a1b9 100644 --- a/drivers/staging/comedi/drivers/addi_apci_1500.c +++ b/drivers/staging/comedi/drivers/addi_apci_1500.c @@ -456,9 +456,9 @@ static int apci1500_di_cfg_trig(struct comedi_device *dev, unsigned int lo_mask = data[5] << shift; unsigned int chan_mask = hi_mask | lo_mask; unsigned int old_mask = (1 << shift) - 1; - unsigned int pm = devpriv->pm[trig] & old_mask; - unsigned int pt = devpriv->pt[trig] & old_mask; - unsigned int pp = devpriv->pp[trig] & old_mask; + unsigned int pm; + unsigned int pt; + unsigned int pp; if (trig > 1) { dev_dbg(dev->class_dev, @@ -471,6 +471,10 @@ static int apci1500_di_cfg_trig(struct comedi_device *dev, return -EINVAL; } + pm = devpriv->pm[trig] & old_mask; + pt = devpriv->pt[trig] & old_mask; + pp = devpriv->pp[trig] & old_mask; + switch (data[2]) { case COMEDI_DIGITAL_TRIG_DISABLE: /* clear trigger configuration */ -- 2.27.0