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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c
index 0a12d46dc517ceca9b48db44b2a62af9e30b68b9..482c126d634125acce9ae7019ab2671fe8360492 100644 (file)
--- a/drivers/target/target_core_cdb.c
+++ b/drivers/target/target_core_cdb.c
@@ -1013,7 +1013,6 @@ int target_emulate_unmap(struct se_cmd *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;
@@ -1029,11 +1028,12 @@ int target_emulate_unmap(struct se_cmd *cmd)
        /* 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);