[ 3.5.yuz extended stable ] Patch "target: fix truncation of mode data, support zero allocation" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    target: fix truncation of mode data, support zero allocation

to the linux-3.5.y-queue branch of the 3.5.yuz extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.yuz tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 6ab72bb6e88fda121249a59c2ec41169287d2cf8 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini at redhat.com>
Date: Fri, 7 Sep 2012 17:30:39 +0200
Subject: [PATCH] target: fix truncation of mode data, support zero allocation
 length

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 at redhat.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
[ herton: backported, code to be patched is on target_core_cdb.c,
  target_emulate_modesense, the function was moved/renamed later ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/target/target_core_cdb.c |   17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c
index 5b20579..3dc3393 100644
--- a/drivers/target/target_core_cdb.c
+++ b/drivers/target/target_core_cdb.c
@@ -856,7 +856,7 @@ int target_emulate_modesense(struct se_cmd *cmd)
 	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];

@@ -889,6 +889,7 @@ int target_emulate_modesense(struct se_cmd *cmd)
 		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 &&
@@ -898,13 +899,10 @@ int target_emulate_modesense(struct se_cmd *cmd)
 		if ((dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0) &&
 		    (dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0))
 			target_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 &&
@@ -914,14 +912,13 @@ int target_emulate_modesense(struct se_cmd *cmd)
 		if ((dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0) &&
 		    (dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0))
 			target_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;
--
1.7.9.5