target: Fix reading of data length fields for UNMAP commands

commit 1a5fa4576ec8a462313c7516b31d7453481ddbe8 upstream.

The UNMAP DATA LENGTH and UNMAP BLOCK DESCRIPTOR DATA LENGTH fields
are in the unmap descriptor (the payload transferred to our data out
buffer), not in the CDB itself.  Read them from the correct place in
target_emulated_unmap.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c
index 45a3ed4b5887287b64026f45ab9496a77ff5739f..b1f5cf010a296562067b06d41795b984be33c7be 100644 (file)
--- a/drivers/target/target_core_cdb.c
+++ b/drivers/target/target_core_cdb.c
@@ -1114,7 +1114,6 @@ int target_emulate_unmap(struct se_task *task)
        struct se_cmd *cmd = task->task_se_cmd;
        struct se_device *dev = cmd->se_dev;
        unsigned char *buf, *ptr = NULL;
-       unsigned char *cdb = &cmd->t_task_cdb[0];
        sector_t lba;
        unsigned int size = cmd->data_length, range;
        int ret = 0, offset;
@@ -1130,11 +1129,12 @@ int target_emulate_unmap(struct se_task *task)
        /* First UNMAP block descriptor starts at 8 byte offset */
        offset = 8;
        size -= 8;
-       dl = get_unaligned_be16(&cdb[0]);
-       bd_dl = get_unaligned_be16(&cdb[2]);
 
        buf = transport_kmap_data_sg(cmd);
 
+       dl = get_unaligned_be16(&buf[0]);
+       bd_dl = get_unaligned_be16(&buf[2]);
+
        ptr = &buf[offset];
        pr_debug("UNMAP: Sub: %s Using dl: %hu bd_dl: %hu size: %hu"
                " ptr: %p\n", dev->transport->name, dl, bd_dl, size, ptr);