[PATCH 3/3] drivers/scsi: Add kmalloc NULL tests

[PATCH 3/3] drivers/scsi: Add kmalloc NULL tests

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

Check that the result of kmalloc is not NULL before passing it to other
functions.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression *x;
identifier f;
constant char *C;
@@

x = \(kmalloc\|kcalloc\|kzalloc\)(...);
... when != x == NULL
    when != x != NULL
    when != (x || ...)
(
kfree(x)
|
f(...,C,...,x,...)
|
*f(...,x,...)
|
*x->f
)
// </smpl>

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

---
 drivers/scsi/sr.c                   |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index cce0fe4..3fbf42e 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -211,6 +211,8 @@ static int sr_media_change(struct cdrom_device_info *cdi, int slot)
 	}
 
 	sshdr =  kzalloc(sizeof(*sshdr), GFP_KERNEL);
+	if (!sshdr)
+		return -ENOMEM;
 	retval = sr_test_unit_ready(cd->device, sshdr);
 	if (retval || (scsi_sense_valid(sshdr) &&
 		       /* 0x3a is medium not present */

Re: [PATCH 3/3] drivers/scsi: Add kmalloc NULL tests

[James Bottomley]

On Thu, 2009-08-06 at 22:06 +0200, Julia Lawall wrote:
> From: Julia Lawall <julia@diku.dk>
> 
> Check that the result of kmalloc is not NULL before passing it to other
> functions.
> 
> The semantic match that finds this problem is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @@
> expression *x;
> identifier f;
> constant char *C;
> @@
> 
> x = \(kmalloc\|kcalloc\|kzalloc\)(...);
> ... when != x == NULL
>     when != x != NULL
>     when != (x || ...)
> (
> kfree(x)
> |
> f(...,C,...,x,...)
> |
> *f(...,x,...)
> |
> *x->f
> )
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>
> 
> ---
>  drivers/scsi/sr.c                   |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
> index cce0fe4..3fbf42e 100644
> --- a/drivers/scsi/sr.c
> +++ b/drivers/scsi/sr.c
> @@ -211,6 +211,8 @@ static int sr_media_change(struct cdrom_device_info *cdi, int slot)
>  	}
>  
>  	sshdr =  kzalloc(sizeof(*sshdr), GFP_KERNEL);
> +	if (!sshdr)
> +		return -ENOMEM;

this isn't necessary; sr_test_unit_ready is designed to take a NULL
pointer for sshdr ... it's just slightly less useful when this happens,
but it still returns some status.

James


>  	retval = sr_test_unit_ready(cd->device, sshdr);
>  	if (retval || (scsi_sense_valid(sshdr) &&
>  		       /* 0x3a is medium not present */
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 3/3] drivers/scsi: Add kmalloc NULL tests

[Julia Lawall]

On Thu, 6 Aug 2009, James Bottomley wrote:

> On Thu, 2009-08-06 at 22:06 +0200, Julia Lawall wrote:
> > From: Julia Lawall <julia@diku.dk>
> > 
> > Check that the result of kmalloc is not NULL before passing it to other
> > functions.
> > 
> > The semantic match that finds this problem is as follows:
> > (http://coccinelle.lip6.fr/)
> > 
> > // <smpl>
> > @@
> > expression *x;
> > identifier f;
> > constant char *C;
> > @@
> > 
> > x = \(kmalloc\|kcalloc\|kzalloc\)(...);
> > ... when != x == NULL
> >     when != x != NULL
> >     when != (x || ...)
> > (
> > kfree(x)
> > |
> > f(...,C,...,x,...)
> > |
> > *f(...,x,...)
> > |
> > *x->f
> > )
> > // </smpl>
> > 
> > Signed-off-by: Julia Lawall <julia@diku.dk>
> > 
> > ---
> >  drivers/scsi/sr.c                   |    2 ++
> >  1 files changed, 2 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
> > index cce0fe4..3fbf42e 100644
> > --- a/drivers/scsi/sr.c
> > +++ b/drivers/scsi/sr.c
> > @@ -211,6 +211,8 @@ static int sr_media_change(struct cdrom_device_info *cdi, int slot)
> >  	}
> >  
> >  	sshdr =  kzalloc(sizeof(*sshdr), GFP_KERNEL);
> > +	if (!sshdr)
> > +		return -ENOMEM;
> 
> this isn't necessary; sr_test_unit_ready is designed to take a NULL
> pointer for sshdr ... it's just slightly less useful when this happens,
> but it still returns some status.

OK, I agree.  Thanks.

julia