[PATCH v3 1/2] scsi: sd: Fix potential NULL pointer dereference

Damien Le Moal
2022-06-01T06:25:52Z

If sd_probe() sees an early error before sdkp->device is initialized,
sd_zbc_release_disk() is called. This causes a NULL pointer dereference
when sd_is_zoned() is called inside that function. Avoid this by
removing the call to sd_zbc_release_disk() in sd_probe() error path.

This chnage is safe and does not result in zone information memory
leakage because the zone information for a zoned disk is allocated only
when sd_revalidate_disk() is called, at which point sdkp->disk_dev is
fully set, resulting in sd_disk_release() being called when needed to
cleanup a disk zone information using sd_zbc_release_disk().

Reported-by: Dongliang Mu <mudongliangabcd@gmail.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Fixes: 89d947561077 ("sd: Implement support for ZBC device")
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
---
drivers/scsi/sd.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 749316462075..dabdc0eeb3dc 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3542,7 +3542,6 @@ static int sd_probe(struct device *dev)
out_put:
put_disk(gd);
out_free:
- sd_zbc_release_disk(sdkp);
kfree(sdkp);
out:
scsi_autopm_put_device(sdp);
--
2.36.1