2009-12-14 16:46:11

by Alexander Strakh

Subject: BUG null dereference in drivers/ata/sata_mv.c

KERNEL_VERSION: 2.6.32
SUBJECT: null dereference in function mv_unexpected_intr
DESCRIBE:
In ./drivers/ata/sata_mv.c in function mv_port_intr

1. If ap == NULL in line 2778, then we goto line 2779.
2. In line 2779 function mv_unexpected_intr(ap, 0) is called.
3. In line 2538 null dereference: "ap->link.eh_info"

2773 static void mv_port_intr(struct ata_port *ap, u32 port_cause)
2774 {
...
2778 if (!ap || (ap->flags & ATA_FLAG_DISABLED)) {
2779 mv_unexpected_intr(ap, 0);
2780 return;
2781 }
...
2809 }

2536 static void mv_unexpected_intr(struct ata_port *ap, int edma_was_enabled)
2537 {
2538 struct ata_eh_info *ehi = &ap->link.eh_info;
...
2555 }

Found by Linux Device Drivers Verification Project (Svace Detector)

2009-12-15 01:34:55

by Robert Hancock

Subject: Re: BUG null dereference in drivers/ata/sata_mv.c

On 12/14/2009 02:51 PM, Alexander Strakh wrote:
> KERNEL_VERSION: 2.6.32
> SUBJECT: null dereference in function mv_unexpected_intr
> DESCRIBE:
> In ./drivers/ata/sata_mv.c in function mv_port_intr
>
> 1. If ap == NULL in line 2778, then we goto line 2779.
> 2. In line 2779 function mv_unexpected_intr(ap, 0) is called.
> 3. In line 2538 null dereference: "ap->link.eh_info"
>
> 2773 static void mv_port_intr(struct ata_port *ap, u32 port_cause)
> 2774 {
> ...
> 2778 if (!ap || (ap->flags& ATA_FLAG_DISABLED)) {
> 2779 mv_unexpected_intr(ap, 0);
> 2780 return;
> 2781 }
> ...
> 2809 }
>
> 2536 static void mv_unexpected_intr(struct ata_port *ap, int edma_was_enabled)
> 2537 {
> 2538 struct ata_eh_info *ehi =&ap->link.eh_info;
> ...
> 2555 }
>
> Found by Linux Device Drivers Verification Project (Svace Detector)

I don't think it should be possible for ap to be null at the point the
check is made. The null check could likely be removed.

2009-12-17 06:25:23

by Jeff Garzik

Subject: Re: BUG null dereference in drivers/ata/sata_mv.c

On 12/14/2009 03:51 PM, Alexander Strakh wrote:
> KERNEL_VERSION: 2.6.32
> SUBJECT: null dereference in function mv_unexpected_intr
> DESCRIBE:
> In ./drivers/ata/sata_mv.c in function mv_port_intr
>
> 1. If ap == NULL in line 2778, then we goto line 2779.
> 2. In line 2779 function mv_unexpected_intr(ap, 0) is called.
> 3. In line 2538 null dereference: "ap->link.eh_info"
>
> 2773 static void mv_port_intr(struct ata_port *ap, u32 port_cause)
> 2774 {
> ...
> 2778 if (!ap || (ap->flags& ATA_FLAG_DISABLED)) {
> 2779 mv_unexpected_intr(ap, 0);
> 2780 return;

pointless null test removed...