Patch "tcmu: Fix possible overwrite of t_data_sg's last iov[]" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    tcmu: Fix possible overwrite of t_data_sg's last iov[]

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tcmu-fix-possible-overwrite-of-t_data_sg-s-last-iov.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ab22d2604c86ceb01bb2725c9860b88a7dd383bb Mon Sep 17 00:00:00 2001
From: Xiubo Li <lixiubo@cmss.chinamobile.com>
Date: Mon, 27 Mar 2017 17:07:40 +0800
Subject: tcmu: Fix possible overwrite of t_data_sg's last iov[]

From: Xiubo Li <lixiubo@cmss.chinamobile.com>

commit ab22d2604c86ceb01bb2725c9860b88a7dd383bb upstream.

If there has BIDI data, its first iov[] will overwrite the last
iov[] for se_cmd->t_data_sg.

To fix this, we can just increase the iov pointer, but this may
introuduce a new memory leakage bug: If the se_cmd->data_length
and se_cmd->t_bidi_data_sg->length are all not aligned up to the
DATA_BLOCK_SIZE, the actual length needed maybe larger than just
sum of them.

So, this could be avoided by rounding all the data lengthes up
to DATA_BLOCK_SIZE.

Reviewed-by: Mike Christie <mchristi@redhat.com>
Tested-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Reviewed-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Signed-off-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/target/target_core_user.c |   34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -389,6 +389,20 @@ static bool is_ring_space_avail(struct t
 	return true;
 }
 
+static inline size_t tcmu_cmd_get_data_length(struct tcmu_cmd *tcmu_cmd)
+{
+	struct se_cmd *se_cmd = tcmu_cmd->se_cmd;
+	size_t data_length = round_up(se_cmd->data_length, DATA_BLOCK_SIZE);
+
+	if (se_cmd->se_cmd_flags & SCF_BIDI) {
+		BUG_ON(!(se_cmd->t_bidi_data_sg && se_cmd->t_bidi_data_nents));
+		data_length += round_up(se_cmd->t_bidi_data_sg->length,
+				DATA_BLOCK_SIZE);
+	}
+
+	return data_length;
+}
+
 static sense_reason_t
 tcmu_queue_cmd_ring(struct tcmu_cmd *tcmu_cmd)
 {
@@ -402,7 +416,7 @@ tcmu_queue_cmd_ring(struct tcmu_cmd *tcm
 	uint32_t cmd_head;
 	uint64_t cdb_off;
 	bool copy_to_data_area;
-	size_t data_length;
+	size_t data_length = tcmu_cmd_get_data_length(tcmu_cmd);
 	DECLARE_BITMAP(old_bitmap, DATA_BLOCK_BITS);
 
 	if (test_bit(TCMU_DEV_BIT_BROKEN, &udev->flags))
@@ -428,11 +442,6 @@ tcmu_queue_cmd_ring(struct tcmu_cmd *tcm
 
 	mb = udev->mb_addr;
 	cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
-	data_length = se_cmd->data_length;
-	if (se_cmd->se_cmd_flags & SCF_BIDI) {
-		BUG_ON(!(se_cmd->t_bidi_data_sg && se_cmd->t_bidi_data_nents));
-		data_length += se_cmd->t_bidi_data_sg->length;
-	}
 	if ((command_size > (udev->cmdr_size / 2)) ||
 	    data_length > udev->data_size) {
 		pr_warn("TCMU: Request of size %zu/%zu is too big for %u/%zu "
@@ -502,11 +511,14 @@ tcmu_queue_cmd_ring(struct tcmu_cmd *tcm
 	entry->req.iov_dif_cnt = 0;
 
 	/* Handle BIDI commands */
-	iov_cnt = 0;
-	alloc_and_scatter_data_area(udev, se_cmd->t_bidi_data_sg,
-		se_cmd->t_bidi_data_nents, &iov, &iov_cnt, false);
-	entry->req.iov_bidi_cnt = iov_cnt;
-
+	if (se_cmd->se_cmd_flags & SCF_BIDI) {
+		iov_cnt = 0;
+		iov++;
+		alloc_and_scatter_data_area(udev, se_cmd->t_bidi_data_sg,
+				se_cmd->t_bidi_data_nents, &iov, &iov_cnt,
+				false);
+		entry->req.iov_bidi_cnt = iov_cnt;
+	}
 	/* cmd's data_bitmap is what changed in process */
 	bitmap_xor(tcmu_cmd->data_bitmap, old_bitmap, udev->data_bitmap,
 			DATA_BLOCK_BITS);


Patches currently in stable-queue which might be from lixiubo@cmss.chinamobile.com are

queue-4.9/tcmu-fix-wrongly-calculating-of-the-base_command_size.patch
queue-4.9/tcmu-fix-possible-overwrite-of-t_data_sg-s-last-iov.patch
queue-4.9/tcmu-skip-data-out-blocks-before-gathering-data-in-buffer-for-bidi-case.patch