iscsi-target: Fix residual count hanlding + remove iscsi_cmd->residual_count

This patch fixes iscsi-target handling of underflow where residual data is
causing an OOPs by using the incorrect iscsi_cmd_t->data_length initially
assigned in iscsit_allocate_se_cmd().  It resets iscsi_cmd_t->data_length
from se_cmd_t->data_length after transport_generic_allocate_tasks()
has been invoked in iscsit_handle_scsi_cmd() RX context, and converts
iscsi_cmd->residual_count usage to access iscsi_cmd->se_cmd.residual_count
to get the proper residual count set by target-core.

Reported-by: <lists@internyc.net>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andy Grover <agrover@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 4d81e1007c9203300406159277aed694e0541b5a..26834eff8960d4718036575c36992e1cccbaf42b 100644 (file)
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1039,6 +1039,8 @@ done:
                 */
                send_check_condition = 1;
        } else {
+               cmd->data_length = cmd->se_cmd.data_length;
+
                if (iscsit_decide_list_to_build(cmd, payload_length) < 0)
                        return iscsit_add_reject_from_cmd(
                                ISCSI_REASON_BOOKMARK_NO_RESOURCES,
@@ -2508,10 +2510,10 @@ static int iscsit_send_data_in(
        if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
                if (cmd->se_cmd.se_cmd_flags & SCF_OVERFLOW_BIT) {
                        hdr->flags |= ISCSI_FLAG_DATA_OVERFLOW;
-                       hdr->residual_count = cpu_to_be32(cmd->residual_count);
+                       hdr->residual_count = cpu_to_be32(cmd->se_cmd.residual_count);
                } else if (cmd->se_cmd.se_cmd_flags & SCF_UNDERFLOW_BIT) {
                        hdr->flags |= ISCSI_FLAG_DATA_UNDERFLOW;
-                       hdr->residual_count = cpu_to_be32(cmd->residual_count);
+                       hdr->residual_count = cpu_to_be32(cmd->se_cmd.residual_count);
                }
        }
        hton24(hdr->dlength, datain.length);
@@ -3013,10 +3015,10 @@ static int iscsit_send_status(
        hdr->flags              |= ISCSI_FLAG_CMD_FINAL;
        if (cmd->se_cmd.se_cmd_flags & SCF_OVERFLOW_BIT) {
                hdr->flags |= ISCSI_FLAG_CMD_OVERFLOW;
-               hdr->residual_count = cpu_to_be32(cmd->residual_count);
+               hdr->residual_count = cpu_to_be32(cmd->se_cmd.residual_count);
        } else if (cmd->se_cmd.se_cmd_flags & SCF_UNDERFLOW_BIT) {
                hdr->flags |= ISCSI_FLAG_CMD_UNDERFLOW;
-               hdr->residual_count = cpu_to_be32(cmd->residual_count);
+               hdr->residual_count = cpu_to_be32(cmd->se_cmd.residual_count);
        }
        hdr->response           = cmd->iscsi_response;
        hdr->cmd_status         = cmd->se_cmd.scsi_status;

diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
index 3723d90d5ae573db84b658fbd70bf2cd7a82bafa..0e96a6b131741bf392008dacb37a2fa5f7d6a743 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_core.h
+++ b/drivers/target/iscsi/iscsi_target_core.h
@@ -398,7 +398,6 @@ struct iscsi_cmd {
        u32                     pdu_send_order;
        /* Current struct iscsi_pdu in struct iscsi_cmd->pdu_list */
        u32                     pdu_start;
-       u32                     residual_count;
        /* Next struct iscsi_seq to send in struct iscsi_cmd->seq_list */
        u32                     seq_send_order;
        /* Number of struct iscsi_seq in struct iscsi_cmd->seq_list */