iscsi-target: Disable markers + remove dangerous local scope array usage

This patch makes iscsi-target explictly disable OFMarker=Yes and IFMarker=yes
parameter key usage during iscsi login by setting IFMarkInt_Reject and
OFMarkInt_Reject values in iscsi_enforce_integrity_rules() to effectively
disable iscsi marker usage.  With this patch, an initiator proposer asking
to enable either marker parameter keys will be issued a 'No' response, and
the target sets OFMarkInt + IFMarkInt parameter key response to 'Irrelevant'.

With markers disabled during iscsi login, this patch removes the problematic
on-stack local-scope array for marker intervals in iscsit_do_rx_data() +
iscsit_do_tx_data(), and other related marker code in iscsi_target_util.c.
This fixes a potentional stack smashing scenario with small range markers
enabled and a large MRDSL as reported by DanC here:

[bug report] target: stack can be smashed
http://www.spinics.net/lists/target-devel/msg00453.html

Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

2 files changed, 7 insertions, 243 deletions

diff --git a/drivers/target/iscsi/iscsi_target_parameters.c b/drivers/target/iscsi/iscsi_target_parameters.c
index 497b2e718a76..5b773160200f 100644
--- a/drivers/target/iscsi/iscsi_target_parameters.c
+++ b/drivers/target/iscsi/iscsi_target_parameters.c
@@ -1430,7 +1430,7 @@ static int iscsi_enforce_integrity_rules(
         u8 DataSequenceInOrder = 0;
         u8 ErrorRecoveryLevel = 0, SessionType = 0;
         u8 IFMarker = 0, OFMarker = 0;
-        u8 IFMarkInt_Reject = 0, OFMarkInt_Reject = 0;
+        u8 IFMarkInt_Reject = 1, OFMarkInt_Reject = 1;
         u32 FirstBurstLength = 0, MaxBurstLength = 0;
         struct iscsi_param *param = NULL;
 
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index a0d23bc0fc98..1d1b4fe33e43 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -875,40 +875,6 @@ void iscsit_inc_session_usage_count(struct iscsi_session *sess)
 }
 
 /*
- *      Used before iscsi_do[rx,tx]_data() to determine iov and [rx,tx]_marker
- *      array counts needed for sync and steering.
- */
-static int iscsit_determine_sync_and_steering_counts(
-        struct iscsi_conn *conn,
-        struct iscsi_data_count *count)
-{
-        u32 length = count->data_length;
-        u32 marker, markint;
-
-        count->sync_and_steering = 1;
-
-        marker = (count->type == ISCSI_RX_DATA) ?
-                        conn->of_marker : conn->if_marker;
-        markint = (count->type == ISCSI_RX_DATA) ?
-                        (conn->conn_ops->OFMarkInt * 4) :
-                        (conn->conn_ops->IFMarkInt * 4);
-        count->ss_iov_count = count->iov_count;
-
-        while (length > 0) {
-                if (length >= marker) {
-                        count->ss_iov_count += 3;
-                        count->ss_marker_count += 2;
-
-                        length -= marker;
-                        marker = markint;
-                } else
-                        length = 0;
-        }
-
-        return 0;
-}
-
-/*
  *      Setup conn->if_marker and conn->of_marker values based upon
  *      the initial marker-less interval. (see iSCSI v19 A.2)
  */
@@ -1431,8 +1397,7 @@ static int iscsit_do_rx_data(
         struct iscsi_data_count *count)
 {
         int data = count->data_length, rx_loop = 0, total_rx = 0, iov_len;
-        u32 rx_marker_val[count->ss_marker_count], rx_marker_iov = 0;
-        struct kvec iov[count->ss_iov_count], *iov_p;
+        struct kvec *iov_p;
         struct msghdr msg;
 
         if (!conn || !conn->sock || !conn->conn_ops)
@@ -1440,93 +1405,8 @@ static int iscsit_do_rx_data(
 
         memset(&msg, 0, sizeof(struct msghdr));
 
-        if (count->sync_and_steering) {
-                int size = 0;
-                u32 i, orig_iov_count = 0;
-                u32 orig_iov_len = 0, orig_iov_loc = 0;
-                u32 iov_count = 0, per_iov_bytes = 0;
-                u32 *rx_marker, old_rx_marker = 0;
-                struct kvec *iov_record;
-
-                memset(&rx_marker_val, 0,
-                                count->ss_marker_count * sizeof(u32));
-                memset(&iov, 0, count->ss_iov_count * sizeof(struct kvec));
-
-                iov_record = count->iov;
-                orig_iov_count = count->iov_count;
-                rx_marker = &conn->of_marker;
-
-                i = 0;
-                size = data;
-                orig_iov_len = iov_record[orig_iov_loc].iov_len;
-                while (size > 0) {
-                        pr_debug("rx_data: #1 orig_iov_len %u,"
-                        " orig_iov_loc %u\n", orig_iov_len, orig_iov_loc);
-                        pr_debug("rx_data: #2 rx_marker %u, size"
-                                " %u\n", *rx_marker, size);
-
-                        if (orig_iov_len >= *rx_marker) {
-                                iov[iov_count].iov_len = *rx_marker;
-                                iov[iov_count++].iov_base =
-                                        (iov_record[orig_iov_loc].iov_base +
-                                                per_iov_bytes);
-
-                                iov[iov_count].iov_len = (MARKER_SIZE / 2);
-                                iov[iov_count++].iov_base =
-                                        &rx_marker_val[rx_marker_iov++];
-                                iov[iov_count].iov_len = (MARKER_SIZE / 2);
-                                iov[iov_count++].iov_base =
-                                        &rx_marker_val[rx_marker_iov++];
-                                old_rx_marker = *rx_marker;
-
-                                /*
-                                 * OFMarkInt is in 32-bit words.
-                                 */
-                                *rx_marker = (conn->conn_ops->OFMarkInt * 4);
-                                size -= old_rx_marker;
-                                orig_iov_len -= old_rx_marker;
-                                per_iov_bytes += old_rx_marker;
-
-                                pr_debug("rx_data: #3 new_rx_marker"
-                                        " %u, size %u\n", *rx_marker, size);
-                        } else {
-                                iov[iov_count].iov_len = orig_iov_len;
-                                iov[iov_count++].iov_base =
-                                        (iov_record[orig_iov_loc].iov_base +
-                                                per_iov_bytes);
-
-                                per_iov_bytes = 0;
-                                *rx_marker -= orig_iov_len;
-                                size -= orig_iov_len;
-
-                                if (size)
-                                        orig_iov_len =
-                                        iov_record[++orig_iov_loc].iov_len;
-
-                                pr_debug("rx_data: #4 new_rx_marker"
-                                        " %u, size %u\n", *rx_marker, size);
-                        }
-                }
-                data += (rx_marker_iov * (MARKER_SIZE / 2));
-
-                iov_p   = &iov[0];
-                iov_len = iov_count;
-
-                if (iov_count > count->ss_iov_count) {
-                        pr_err("iov_count: %d, count->ss_iov_count:"
-                                " %d\n", iov_count, count->ss_iov_count);
-                        return -1;
-                }
-                if (rx_marker_iov > count->ss_marker_count) {
-                        pr_err("rx_marker_iov: %d, count->ss_marker"
-                                "_count: %d\n", rx_marker_iov,
-                                count->ss_marker_count);
-                        return -1;
-                }
-        } else {
-                iov_p = count->iov;
-                iov_len = count->iov_count;
-        }
+        iov_p = count->iov;
+        iov_len = count->iov_count;
 
         while (total_rx < data) {
                 rx_loop = kernel_recvmsg(conn->sock, &msg, iov_p, iov_len,
@@ -1541,16 +1421,6 @@ static int iscsit_do_rx_data(
                                 rx_loop, total_rx, data);
         }
 
-        if (count->sync_and_steering) {
-                int j;
-                for (j = 0; j < rx_marker_iov; j++) {
-                        pr_debug("rx_data: #5 j: %d, offset: %d\n",
-                                j, rx_marker_val[j]);
-                        conn->of_marker_offset = rx_marker_val[j];
-                }
-                total_rx -= (rx_marker_iov * (MARKER_SIZE / 2));
-        }
-
         return total_rx;
 }
 
@@ -1559,8 +1429,7 @@ static int iscsit_do_tx_data(
         struct iscsi_data_count *count)
 {
         int data = count->data_length, total_tx = 0, tx_loop = 0, iov_len;
-        u32 tx_marker_val[count->ss_marker_count], tx_marker_iov = 0;
-        struct kvec iov[count->ss_iov_count], *iov_p;
+        struct kvec *iov_p;
         struct msghdr msg;
 
         if (!conn || !conn->sock || !conn->conn_ops)
@@ -1573,98 +1442,8 @@ static int iscsit_do_tx_data(
 
         memset(&msg, 0, sizeof(struct msghdr));
 
-        if (count->sync_and_steering) {
-                int size = 0;
-                u32 i, orig_iov_count = 0;
-                u32 orig_iov_len = 0, orig_iov_loc = 0;
-                u32 iov_count = 0, per_iov_bytes = 0;
-                u32 *tx_marker, old_tx_marker = 0;
-                struct kvec *iov_record;
-
-                memset(&tx_marker_val, 0,
-                        count->ss_marker_count * sizeof(u32));
-                memset(&iov, 0, count->ss_iov_count * sizeof(struct kvec));
-
-                iov_record = count->iov;
-                orig_iov_count = count->iov_count;
-                tx_marker = &conn->if_marker;
-
-                i = 0;
-                size = data;
-                orig_iov_len = iov_record[orig_iov_loc].iov_len;
-                while (size > 0) {
-                        pr_debug("tx_data: #1 orig_iov_len %u,"
-                        " orig_iov_loc %u\n", orig_iov_len, orig_iov_loc);
-                        pr_debug("tx_data: #2 tx_marker %u, size"
-                                " %u\n", *tx_marker, size);
-
-                        if (orig_iov_len >= *tx_marker) {
-                                iov[iov_count].iov_len = *tx_marker;
-                                iov[iov_count++].iov_base =
-                                        (iov_record[orig_iov_loc].iov_base +
-                                                per_iov_bytes);
-
-                                tx_marker_val[tx_marker_iov] =
-                                                (size - *tx_marker);
-                                iov[iov_count].iov_len = (MARKER_SIZE / 2);
-                                iov[iov_count++].iov_base =
-                                        &tx_marker_val[tx_marker_iov++];
-                                iov[iov_count].iov_len = (MARKER_SIZE / 2);
-                                iov[iov_count++].iov_base =
-                                        &tx_marker_val[tx_marker_iov++];
-                                old_tx_marker = *tx_marker;
-
-                                /*
-                                 * IFMarkInt is in 32-bit words.
-                                 */
-                                *tx_marker = (conn->conn_ops->IFMarkInt * 4);
-                                size -= old_tx_marker;
-                                orig_iov_len -= old_tx_marker;
-                                per_iov_bytes += old_tx_marker;
-
-                                pr_debug("tx_data: #3 new_tx_marker"
-                                        " %u, size %u\n", *tx_marker, size);
-                                pr_debug("tx_data: #4 offset %u\n",
-                                        tx_marker_val[tx_marker_iov-1]);
-                        } else {
-                                iov[iov_count].iov_len = orig_iov_len;
-                                iov[iov_count++].iov_base
-                                        = (iov_record[orig_iov_loc].iov_base +
-                                                per_iov_bytes);
-
-                                per_iov_bytes = 0;
-                                *tx_marker -= orig_iov_len;
-                                size -= orig_iov_len;
-
-                                if (size)
-                                        orig_iov_len =
-                                        iov_record[++orig_iov_loc].iov_len;
-
-                                pr_debug("tx_data: #5 new_tx_marker"
-                                        " %u, size %u\n", *tx_marker, size);
-                        }
-                }
-
-                data += (tx_marker_iov * (MARKER_SIZE / 2));
-
-                iov_p = &iov[0];
-                iov_len = iov_count;
-
-                if (iov_count > count->ss_iov_count) {
-                        pr_err("iov_count: %d, count->ss_iov_count:"
-                                " %d\n", iov_count, count->ss_iov_count);
-                        return -1;
-                }
-                if (tx_marker_iov > count->ss_marker_count) {
-                        pr_err("tx_marker_iov: %d, count->ss_marker"
-                                "_count: %d\n", tx_marker_iov,
-                                count->ss_marker_count);
-                        return -1;
-                }
-        } else {
-                iov_p = count->iov;
-                iov_len = count->iov_count;
-        }
+        iov_p = count->iov;
+        iov_len = count->iov_count;
 
         while (total_tx < data) {
                 tx_loop = kernel_sendmsg(conn->sock, &msg, iov_p, iov_len,
@@ -1679,9 +1458,6 @@ static int iscsit_do_tx_data(
                                         tx_loop, total_tx, data);
         }
 
-        if (count->sync_and_steering)
-                total_tx -= (tx_marker_iov * (MARKER_SIZE / 2));
-
         return total_tx;
 }
 
@@ -1702,12 +1478,6 @@ int rx_data(
         c.data_length = data;
         c.type = ISCSI_RX_DATA;
 
-        if (conn->conn_ops->OFMarker &&
-           (conn->conn_state >= TARG_CONN_STATE_LOGGED_IN)) {
-                if (iscsit_determine_sync_and_steering_counts(conn, &c) < 0)
-                        return -1;
-        }
-
         return iscsit_do_rx_data(conn, &c);
 }
 
@@ -1728,12 +1498,6 @@ int tx_data(
         c.data_length = data;
         c.type = ISCSI_TX_DATA;
 
-        if (conn->conn_ops->IFMarker &&
-           (conn->conn_state >= TARG_CONN_STATE_LOGGED_IN)) {
-                if (iscsit_determine_sync_and_steering_counts(conn, &c) < 0)
-                        return -1;
-        }
-
         return iscsit_do_tx_data(conn, &c);
 }