[3.16.y-ckt stable] Patch "iser-target: Fix NULL dereference in SW mode DIF" has been added to staging queue

[Luis Henriques]

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

    iser-target: Fix NULL dereference in SW mode DIF

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt4.

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

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 1f463e21d61b68bb55592ea433e5a58f936410e7 Mon Sep 17 00:00:00 2001
From: Sagi Grimberg <sagig at mellanox.com>
Date: Tue, 2 Dec 2014 16:57:34 +0200
Subject: iser-target: Fix NULL dereference in SW mode DIF

commit 302cc7c3ca14d21ccdffdebdb61c4fe028f2d5ad upstream.

Fallback to software mode DIF if HCA does not support
PI (without crashing obviously). It is still possible to
run with backend protection and an unprotected frontend,
so looking at the command prot_op is not enough. Check
device PI capability on a per-IO basis (isert_prot_cmd
inline static) to determine if we need to handle protection
information.

Trace:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
IP: [<ffffffffa037f8b1>] isert_reg_sig_mr+0x351/0x3b0 [ib_isert]
Call Trace:
 [<ffffffff812b003a>] ? swiotlb_map_sg_attrs+0x7a/0x130
 [<ffffffffa038184d>] isert_reg_rdma+0x2fd/0x370 [ib_isert]
 [<ffffffff8108f2ec>] ? idle_balance+0x6c/0x2c0
 [<ffffffffa0382b68>] isert_put_datain+0x68/0x210 [ib_isert]
 [<ffffffffa02acf5b>] lio_queue_data_in+0x2b/0x30 [iscsi_target_mod]
 [<ffffffffa02306eb>] target_complete_ok_work+0x21b/0x310 [target_core_mod]
 [<ffffffff8106ece2>] process_one_work+0x182/0x3b0
 [<ffffffff8106fda0>] worker_thread+0x120/0x3c0
 [<ffffffff8106fc80>] ? maybe_create_worker+0x190/0x190
 [<ffffffff8107594e>] kthread+0xce/0xf0
 [<ffffffff81075880>] ? kthread_freezable_should_stop+0x70/0x70
 [<ffffffff8159a22c>] ret_from_fork+0x7c/0xb0
 [<ffffffff81075880>] ? kthread_freezable_should_stop+0x70/0x70

Reported-by: Slava Shwartsman <valyushash at gmail.com>
Signed-off-by: Sagi Grimberg <sagig at mellanox.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/infiniband/ulp/isert/ib_isert.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 703c957683b1..8a25ebee717a 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -61,6 +61,14 @@ static int
 isert_rdma_accept(struct isert_conn *isert_conn);
 struct rdma_cm_id *isert_setup_id(struct isert_np *isert_np);

+static inline bool
+isert_prot_cmd(struct isert_conn *conn, struct se_cmd *cmd)
+{
+	return (conn->conn_device->pi_capable &&
+		cmd->prot_op != TARGET_PROT_NORMAL);
+}
+
+
 static void
 isert_qp_event_callback(struct ib_event *e, void *context)
 {
@@ -2930,8 +2938,7 @@ isert_reg_rdma(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	if (ret)
 		return ret;

-	if (wr->data.dma_nents != 1 ||
-	    se_cmd->prot_op != TARGET_PROT_NORMAL) {
+	if (wr->data.dma_nents != 1 || isert_prot_cmd(isert_conn, se_cmd)) {
 		spin_lock_irqsave(&isert_conn->conn_lock, flags);
 		fr_desc = list_first_entry(&isert_conn->conn_fr_pool,
 					   struct fast_reg_descriptor, list);
@@ -2945,7 +2952,7 @@ isert_reg_rdma(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	if (ret)
 		goto unmap_cmd;

-	if (se_cmd->prot_op != TARGET_PROT_NORMAL) {
+	if (isert_prot_cmd(isert_conn, se_cmd)) {
 		ret = isert_handle_prot_cmd(isert_conn, isert_cmd, wr);
 		if (ret)
 			goto unmap_cmd;
@@ -2970,7 +2977,7 @@ isert_reg_rdma(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 		send_wr->opcode = IB_WR_RDMA_WRITE;
 		send_wr->wr.rdma.remote_addr = isert_cmd->read_va;
 		send_wr->wr.rdma.rkey = isert_cmd->read_stag;
-		send_wr->send_flags = se_cmd->prot_op == TARGET_PROT_NORMAL ?
+		send_wr->send_flags = !isert_prot_cmd(isert_conn, se_cmd) ?
 				      0 : IB_SEND_SIGNALED;
 	} else {
 		send_wr->opcode = IB_WR_RDMA_READ;
@@ -3012,7 +3019,7 @@ isert_put_datain(struct iscsi_conn *conn, struct iscsi_cmd *cmd)
 		return rc;
 	}

-	if (se_cmd->prot_op == TARGET_PROT_NORMAL) {
+	if (!isert_prot_cmd(isert_conn, se_cmd)) {
 		/*
 		 * Build isert_conn->tx_desc for iSCSI response PDU and attach
 		 */
@@ -3035,7 +3042,7 @@ isert_put_datain(struct iscsi_conn *conn, struct iscsi_cmd *cmd)
 		atomic_sub(wr->send_wr_num, &isert_conn->post_send_buf_count);
 	}

-	if (se_cmd->prot_op == TARGET_PROT_NORMAL)
+	if (!isert_prot_cmd(isert_conn, se_cmd))
 		pr_debug("Cmd: %p posted RDMA_WRITE + Response for iSER Data "
 			 "READ\n", isert_cmd);
 	else
--
2.1.4