ata_msense_control_spgt2() can be called even for devices that do not
support CDL when the user requests the ALL_SUB_MPAGES mode sense page,
but for such device, this will cause a NULL pointer dereference as
dev->cdl is NULL. Similarly, we should not return any data if
ata_msense_control_spgt2() is called when the user requested the
CDL_T2A_SUB_MPAGE or CDL_T2B_SUB_MPAGE pages for a device that does not
support CDL.
Avoid this potential NULL pointer dereference by checking if the device
support CDL on entry to ata_msense_control_spgt2() and return 0 if it
does not support CDL.
Reported-by: syzbot+37757dc11ee77ef850bb@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: syzbot+37757dc11ee77ef850bb@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 602bcf212637 ("ata: libata: Improve CDL resource management")
Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
---
drivers/ata/libata-scsi.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 061fe63497bf..97c84b0ec472 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2245,10 +2245,15 @@ static inline u16 ata_xlat_cdl_limit(u8 *buf)
static unsigned int ata_msense_control_spgt2(struct ata_device *dev, u8 *buf,
u8 spg)
{
- u8 *b, *cdl = dev->cdl->desc_log_buf, *desc;
+ u8 *b, *cdl, *desc;
u32 policy;
int i;
+ if (!(dev->flags & ATA_DFLAG_CDL) || !dev->cdl)
+ return 0;
+
+ cdl = dev->cdl->desc_log_buf;
+
/*
* Fill the subpage. The first four bytes of the T2A/T2B mode pages
* are a header. The PAGE LENGTH field is the size of the page
--
2.46.0
