Re: [PATCH] scsi: megaraid: Fix null dereference

[Igor A. Artemiev]

On 4/3/23 18:19, James Bottomley wrote:
> On Mon, 2023-04-03 at 17:34 +0300, Igor Artemiev wrote:
> > When cmdid == CMDID_INT_CMDS, the 'mbox' pointer is NULL but is
> > dereferenced below.
> >
> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> >
> > Fixes: 0f2bb84d2a68 ("[SCSI] megaraid: simplify internal command
> > handling")
> > Signed-off-by: Igor Artemiev <Igor.A.Artemiev@xxxxxxx>
> > ---
> >   drivers/scsi/megaraid.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/scsi/megaraid.c b/drivers/scsi/megaraid.c
> > index bf491af9f0d6..4fbf92dc717e 100644
> > --- a/drivers/scsi/megaraid.c
> > +++ b/drivers/scsi/megaraid.c
> > @@ -1441,6 +1441,7 @@ mega_cmd_done(adapter_t *adapter, u8
> > completed[], int nstatus, int status)
> >                   */
> >                  if (cmdid == CMDID_INT_CMDS) {
> >                          scb = &adapter->int_scb;
> > +                       mbox = (mbox_t *)scb->raw_mbox;
> Have you actually seen this and if so which firmware?  I thought
> megaraid internal commands only ever returned success or fail (0 or 1)
> meaning they can never get into the sense processing case that is the
> only consumer of the mbox.
>
> James
No, I haven't seen this. A null dereference can be if the 'status'  is 
0x02. But if 'status' cannot be equal to 0x02, assignment isn't required.

Thanks,
Igor