[PATCH v1 0/1] Parfait changes

The following patch(s) are bugs found by the static compiler
'Parfait'.  Care was taken to make sure false positive results
were removed from this patchset.

Parfait Overview
================

https://labs.oracle.com/pls/apex/f?p=labs:49:::::P49_PROJECT_ID:13

v1:
Initial release

Joe Moriarty (1):
  drivers: isdn: NULL pointer dereference [null-pointer-deref] (CWE 476)
    problem

 drivers/isdn/mISDN/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

-- 
2.15.0

The Parfait (version 2.1.0) static code analysis tool found the
following NULL pointer dereference problem.

- drivers/isdn/mISDN/core.c
function channelmap_show() does not check the returned mdev
variable from dev_to_mISDN() for NULL.  Added the check for
NULL, which results in a value of 0 being returned.

Signed-off-by: Joe Moriarty <redacted>
Reviewed-by: Jonathan Helman <redacted>
---
 drivers/isdn/mISDN/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/isdn/mISDN/core.c b/drivers/isdn/mISDN/core.c
index faf505462a4f..aec7e2706109 100644
--- a/drivers/isdn/mISDN/core.c
+++ b/drivers/isdn/mISDN/core.c

@@ -129,8 +129,10 @@ static ssize_t channelmap_show(struct device *dev,
 	char *bp = buf;
 	int i;
 
-	for (i = 0; i <= mdev->nrbchan; i++)
-		*bp++ = test_channelmap(i, mdev->channelmap) ? '1' : '0';
+	if (mdev)
+		for (i = 0; i <= mdev->nrbchan; i++)
+			*bp++ = test_channelmap(i, mdev->channelmap) ?
+				'1' : '0';
 
 	return bp - buf;
 }

-- 
2.15.0

From: Joe Moriarty <redacted>
Date: Thu, 15 Feb 2018 15:27:00 -0500

The Parfait (version 2.1.0) static code analysis tool found the
following NULL pointer dereference problem.

- drivers/isdn/mISDN/core.c
function channelmap_show() does not check the returned mdev
variable from dev_to_mISDN() for NULL.  Added the check for
NULL, which results in a value of 0 being returned.

Signed-off-by: Joe Moriarty <redacted>
Reviewed-by: Jonathan Helman <redacted>

Since the lifetime for the sysfs files for these devices is strictly
smaller than the lifetime of the 'dev' object and it's driver data,
it is not possible for mdev to be NULL in this situation.

I understand what the static checker is trying to do, but within
context this lack of a NULL check is legitimate.

I'm not applying this, sorry.

On 2/16/2018 4:11 PM, David Miller wrote:

From: Joe Moriarty <redacted>
Date: Thu, 15 Feb 2018 15:27:00 -0500

quoted

The Parfait (version 2.1.0) static code analysis tool found the
following NULL pointer dereference problem.

- drivers/isdn/mISDN/core.c
function channelmap_show() does not check the returned mdev
variable from dev_to_mISDN() for NULL.  Added the check for
NULL, which results in a value of 0 being returned.

Signed-off-by: Joe Moriarty <redacted>
Reviewed-by: Jonathan Helman <redacted>

Since the lifetime for the sysfs files for these devices is strictly
smaller than the lifetime of the 'dev' object and it's driver data,
it is not possible for mdev to be NULL in this situation.

I understand what the static checker is trying to do, but within
context this lack of a NULL check is legitimate.

I'm not applying this, sorry.

Thanks for the review David and there is no reason to be sorry.  I'll 
will mark this as a false positive result from our static checker.