On Thu, 2023-07-27 at 18:39 +0300, Alexandra Diupina wrote:
> The 'slot' variable allows a NULL value.
> It is necessary to add a check for a null
> value to avoid dereferencing the null pointer.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Co-developed-by: Vladimir Telezhnikov <vtelezhnikov@xxxxxxxxxxxxx>
> Signed-off-by: Vladimir Telezhnikov <vtelezhnikov@xxxxxxxxxxxxx>
> Signed-off-by: Alexandra Diupina <adiupina@xxxxxxxxxxxxx>
> ---
> drivers/scsi/53c700.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/scsi/53c700.c b/drivers/scsi/53c700.c
> index e1e4f9d10887..8e5468d1733d 100644
> --- a/drivers/scsi/53c700.c
> +++ b/drivers/scsi/53c700.c
> @@ -1598,6 +1598,8 @@ NCR_700_intr(int irq, void *dev_id)
> printk("scsi%d (%d:%d) PHASE MISMATCH
> IN SEND MESSAGE %d remain, return %p[%04x], phase %s\n", host-
> >host_no, pun, lun, count, (void *)temp, temp - hostdata->pScript,
> sbcl_to_string(NCR_700_readb(host, SBCL_REG)));
> #endif
> resume_offset = hostdata->pScript +
> Ent_SendMessagePhaseMismatch;
> + } else if (!slot) {
> + printk(KERN_ERR "53c700: SCSI DONE
> HAS NULL SCp\n");
> } else if(dsp >= to32bit(&slot->pSG[0].ins)
> &&
I don't believe anyone has ever hit this, but if slot were null, it
would have to drop through to the else clause to get a bus reset to
kick the device. If we do what you propose above, the driver would
hang instead of crashing, which isn't a better outcome. Something like
this.
James
---
diff --git a/drivers/scsi/53c700.c b/drivers/scsi/53c700.c
index e1e4f9d10887..5296a13404cf 100644
--- a/drivers/scsi/53c700.c
+++ b/drivers/scsi/53c700.c
@@ -1598,7 +1598,7 @@ NCR_700_intr(int irq, void *dev_id)
printk("scsi%d (%d:%d) PHASE MISMATCH IN SEND MESSAGE %d remain, return %p[%04x], phase %s\n", host->host_no, pun, lun, count, (void *)temp, temp - hostdata->pScript, sbcl_to_string(NCR_700_readb(host, SBCL_REG)));
#endif
resume_offset = hostdata->pScript + Ent_SendMessagePhaseMismatch;
- } else if(dsp >= to32bit(&slot->pSG[0].ins) &&
+ } else if(slot && dsp >= to32bit(&slot->pSG[0].ins) &&
dsp <= to32bit(&slot->pSG[NCR_700_SG_SEGMENTS].ins)) {
int data_transfer = NCR_700_readl(host, DBC_REG) & 0xffffff;
int SGcount = (dsp - to32bit(&slot->pSG[0].ins))/sizeof(struct NCR_700_SG_List);
