[PATCH 7/11] drivers/scsi: Eliminate a NULL pointer dereference

[PATCH 7/11] drivers/scsi: Eliminate a NULL pointer dereference

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

The end of the function is reachable both when host is and is not NULL.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
expression E,E1;
identifier f;
statement S1,S2,S3;
@@

if ((E == NULL && ...) || ...)
{
  ... when != if (...) S1 else S2
      when != E = E1
* E->f
  ... when any
  return ...;
}
else S3
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
If it is a problem to use 0 when host is NULL, then the code could be fixed
in another way.

 drivers/scsi/hptiop.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/hptiop.c b/drivers/scsi/hptiop.c
index 645f7cd..0729f15 100644
--- a/drivers/scsi/hptiop.c
+++ b/drivers/scsi/hptiop.c
@@ -1157,7 +1157,7 @@ free_pci_regions:
 disable_pci_device:
 	pci_disable_device(pcidev);
 
-	dprintk("scsi%d: hptiop_probe fail\n", host->host_no);
+	dprintk("scsi%d: hptiop_probe fail\n", host ? host->host_no : 0);
 	return -ENODEV;
 }
 

Re: [PATCH 7/11] drivers/scsi: Eliminate a NULL pointer dereference

[Dan Carpenter]

On Thu, May 27, 2010 at 02:33:47PM +0200, Julia Lawall wrote:
> If it is a problem to use 0 when host is NULL, then the code could be fixed
> in another way.
> 

Yeah.  It seems like it would be better to give a clearly bogus number.
I would have said -1 but "scsi-1" looks normal so maybe something like 
9999999?

regards,
dan carpenter

Re: [PATCH 7/11] drivers/scsi: Eliminate a NULL pointer dereference

[walter harms]

Dan Carpenter schrieb:
> On Thu, May 27, 2010 at 02:33:47PM +0200, Julia Lawall wrote:
>> If it is a problem to use 0 when host is NULL, then the code could be fixed
>> in another way.
>>
> 
> Yeah.  It seems like it would be better to give a clearly bogus number.
> I would have said -1 but "scsi-1" looks normal so maybe something like 
> 9999999?
> 

lets spend some bytes:

	
	if (host)
		dprintk("scsi%d: hptiop_probe failed\n",host->host_no);
	else
		dprintk("scsi: no host, hptiop_probe failed\n");



re,
 wh

Re: [PATCH 7/11] drivers/scsi: Eliminate a NULL pointer dereference

[Julia Lawall]

On Thu, 27 May 2010, walter harms wrote:

> 
> 
> Dan Carpenter schrieb:
> > On Thu, May 27, 2010 at 02:33:47PM +0200, Julia Lawall wrote:
> >> If it is a problem to use 0 when host is NULL, then the code could be fixed
> >> in another way.
> >>
> > 
> > Yeah.  It seems like it would be better to give a clearly bogus number.
> > I would have said -1 but "scsi-1" looks normal so maybe something like 
> > 9999999?
> > 
> 
> lets spend some bytes:
> 
> 	
> 	if (host)
> 		dprintk("scsi%d: hptiop_probe failed\n",host->host_no);
> 	else
> 		dprintk("scsi: no host, hptiop_probe failed\n");

dprintk is defined in hptiop.h as:

#if 0
#define dprintk(fmt, args...) do { printk(fmt, ##args); } while(0)
#else
#define dprintk(fmt, args...)
#endif

So unless someone adjusts the #if 0, there is no code.  I guess there is a 
danger that adding such an if would actually generate some code?

julia