[PATCH] scsi: mpt2sas: mpt2sas_base.c: Fix for possible null pointer dereference

[PATCH] scsi: mpt2sas: mpt2sas_base.c: Fix for possible null pointer dereference

[Rickard Strandqvist]

There is otherwise a risk of a possible null pointer dereference.

Was largely found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
---
 drivers/scsi/mpt2sas/mpt2sas_base.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.c b/drivers/scsi/mpt2sas/mpt2sas_base.c
index bde63f7..7ccc7e4 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.c
@@ -3581,7 +3581,9 @@ mpt2sas_port_enable_done(struct MPT2SAS_ADAPTER *ioc, u16 smid, u8 msix_index,
 	}
 	ioc->port_enable_cmds.status &= ~MPT2_CMD_PENDING;
 
-	ioc_status = le16_to_cpu(mpi_reply->IOCStatus) & MPI2_IOCSTATUS_MASK;
+	if (mpi_reply) {
+		ioc_status = le16_to_cpu(mpi_reply->IOCStatus) & MPI2_IOCSTATUS_MASK;
+	}
 
 	if (ioc_status != MPI2_IOCSTATUS_SUCCESS)
 		ioc->port_enable_failed = 1;
-- 
1.7.10.4

Re: [PATCH] scsi: mpt2sas: mpt2sas_base.c: Fix for possible null pointer dereference

[Christoph Hellwig]

> -	ioc_status = le16_to_cpu(mpi_reply->IOCStatus) & MPI2_IOCSTATUS_MASK;
> +	if (mpi_reply) {
> +		ioc_status = le16_to_cpu(mpi_reply->IOCStatus) & MPI2_IOCSTATUS_MASK;
> +	}
>  
>  	if (ioc_status != MPI2_IOCSTATUS_SUCCESS)
>  		ioc->port_enable_failed = 1;

ioc_status isn't initialized without the reply and used here as well
as later in the function.  I think we'll need input from LSI or others
with the spec on what to do when we didn't get a reply.

Re: [PATCH] scsi: mpt2sas: mpt2sas_base.c: Fix for possible null pointer dereference

[Joe Lawrence]

On Wed, 28 May 2014, Christoph Hellwig wrote:

> > -	ioc_status = le16_to_cpu(mpi_reply->IOCStatus) & MPI2_IOCSTATUS_MASK;
> > +	if (mpi_reply) {
> > +		ioc_status = le16_to_cpu(mpi_reply->IOCStatus) & MPI2_IOCSTATUS_MASK;
> > +	}
> >  
> >  	if (ioc_status != MPI2_IOCSTATUS_SUCCESS)
> >  		ioc->port_enable_failed = 1;
> 
> ioc_status isn't initialized without the reply and used here as well
> as later in the function.  I think we'll need input from LSI or others
> with the spec on what to do when we didn't get a reply.

Any update on this? 

The mpt3 version checks for !mpi_reply and returns 1.  Which leads to 
another question -- should mpt{2,3}sas_port_enable_done ever return 0 (as their 
respective comments describe)?

Regards,

-- Joe

Re: [PATCH] scsi: mpt2sas: mpt2sas_base.c: Fix for possible null pointer dereference

[Rickard Strandqvist]

2014-07-03 19:45 GMT+02:00 Joe Lawrence <joe.lawrence@stratus.com>:
> On Wed, 28 May 2014, Christoph Hellwig wrote:
>
>> > -   ioc_status = le16_to_cpu(mpi_reply->IOCStatus) & MPI2_IOCSTATUS_MASK;
>> > +   if (mpi_reply) {
>> > +           ioc_status = le16_to_cpu(mpi_reply->IOCStatus) & MPI2_IOCSTATUS_MASK;
>> > +   }
>> >
>> >     if (ioc_status != MPI2_IOCSTATUS_SUCCESS)
>> >             ioc->port_enable_failed = 1;
>>
>> ioc_status isn't initialized without the reply and used here as well
>> as later in the function.  I think we'll need input from LSI or others
>> with the spec on what to do when we didn't get a reply.
>
> Any update on this?
>
> The mpt3 version checks for !mpi_reply and returns 1.  Which leads to
> another question -- should mpt{2,3}sas_port_enable_done ever return 0 (as their
> respective comments describe)?
>
> Regards,
>
> -- Joe


Hi

Good questions Joe!
And good someone else brought this up, because I guess it's not meant to me.

And it looks however now that I've done quite a few more patches that
there should not have been any {}
And then, it is perhaps good to sett a start value for ioc_status. My
suggestion is:

u16 ioc_status = MPI2_IOCSTATUS_OP_STATE_NOT_SUPPORTED;


Kind regards
Rickard Strandqvist