scsi: sd: Fix off-by-one error in sd_read_block_characteristics()

BugLink: https://bugs.launchpad.net/bugs/2089340

commit f81eaf08385ddd474a2f41595a7757502870c0eb upstream.

Ff the device returns page 0xb1 with length 8 (happens with qemu v2.x, for
example), sd_read_block_characteristics() may attempt an out-of-bounds
memory access when accessing the zoned field at offset 8.

Fixes: 7fb019c46e ("scsi: sd: Switch to using scsi_device VPD pages")
Cc: stable@vger.kernel.org
Signed-off-by: Martin Wilck <mwilck@suse.com>
Link: https://lore.kernel.org/r/20240912134308.282824-1-mwilck@suse.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Portia Stephens <portia.stephens@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/scsi/sd.c

@@ -3123,7 +3123,7 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
 	rcu_read_lock();
 	vpd = rcu_dereference(sdkp->device->vpd_pgb1);
 
-	if (!vpd || vpd->len < 8) {
+	if (!vpd || vpd->len <= 8) {
 		rcu_read_unlock();
 	        return;
 	}