[ 30/76] target: fix truncation of mode data, support zero allocation length

Greg Kroah-Hartman
2012-10-19T03:02:30Z

From: Paolo Bonzini <pbonzini@redhat.com>

commit 7a3f369ce31694017996524a1cdb08208a839077 upstream.

The offset was not bumped back to the full size after writing the
header of the MODE SENSE response, so the last 1 or 2 bytes were
not copied.

On top of this, support zero-length requests by checking for the
return value of transport_kmap_data_sg.

Testcase: sg_raw -r20 /dev/sdb 5a 00 0a 00 00 00 00 00 14 00
last byte should be 0x1e
it is 0x00 without the patch
it is correct with the patch

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/target/target_core_spc.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)

--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -784,7 +784,7 @@ static int spc_emulate_modesense(struct
unsigned char *rbuf;
int type = dev->transport->get_device_type(dev);
int ten = (cmd->t_task_cdb[0] == MODE_SENSE_10);
- int offset = ten ? 8 : 4;
+ u32 offset = ten ? 8 : 4;
int length = 0;
unsigned char buf[SE_MODE_PAGE_BUF];

@@ -817,6 +817,7 @@ static int spc_emulate_modesense(struct
offset -= 2;
buf[0] = (offset >> 8) & 0xff;
buf[1] = offset & 0xff;
+ offset += 2;

if ((cmd->se_lun->lun_access & TRANSPORT_LUNFLAGS_READ_ONLY) ||
(cmd->se_deve &&
@@ -826,13 +827,10 @@ static int spc_emulate_modesense(struct
if ((dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0) &&
(dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0))
spc_modesense_dpofua(&buf[3], type);
-
- if ((offset + 2) > cmd->data_length)
- offset = cmd->data_length;
-
} else {
offset -= 1;
buf[0] = offset & 0xff;
+ offset += 1;

if ((cmd->se_lun->lun_access & TRANSPORT_LUNFLAGS_READ_ONLY) ||
(cmd->se_deve &&
@@ -842,14 +840,13 @@ static int spc_emulate_modesense(struct
if ((dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0) &&
(dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0))
spc_modesense_dpofua(&buf[2], type);
-
- if ((offset + 1) > cmd->data_length)
- offset = cmd->data_length;
}

rbuf = transport_kmap_data_sg(cmd);
- memcpy(rbuf, buf, offset);
- transport_kunmap_data_sg(cmd);
+ if (rbuf) {
+ memcpy(rbuf, buf, min(offset, cmd->data_length));
+ transport_kunmap_data_sg(cmd);
+ }

target_complete_cmd(cmd, GOOD);
return 0;