[PATCH 4.1 56/78] target/iscsi: Fix double free of a TUR followed by a solicited NOPOUT

Greg Kroah-Hartman
2015-09-11T22:54:50Z

From: Alexei Potashnik <alexei@purestorage.com>

commit 9547308bda296b6f69876c840a0291fcfbeddbb8 upstream.

Make sure all non-READ SCSI commands get targ_xfer_tag initialized
to 0xffffffff, not just WRITEs.

Double-free of a TUR cmd object occurs under the following scenario:

1. TUR received (targ_xfer_tag is uninitialized and left at 0)
2. TUR status sent
3. First unsolicited NOPIN is sent to initiator (gets targ_xfer_tag of 0)
4. NOPOUT for NOPIN (with TTT=0) arrives
- its ExpStatSN acks TUR status, TUR is queued for removal
- LIO tries to find NOPIN with TTT=0, but finds the same TUR instead,
TUR is queued for removal for the 2nd time

(Drop unbalanced conditional bracket usage - nab)

Signed-off-by: Alexei Potashnik <alexei@purestorage.com>
Signed-off-by: Spencer Baugh <sbaugh@catern.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/target/iscsi/iscsi_target.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -968,9 +968,9 @@ int iscsit_setup_scsi_cmd(struct iscsi_c
cmd->cmd_flags |= ICF_NON_IMMEDIATE_UNSOLICITED_DATA;

conn->sess->init_task_tag = cmd->init_task_tag = hdr->itt;
- if (hdr->flags & ISCSI_FLAG_CMD_READ) {
+ if (hdr->flags & ISCSI_FLAG_CMD_READ)
cmd->targ_xfer_tag = session_get_next_ttt(conn->sess);
- } else if (hdr->flags & ISCSI_FLAG_CMD_WRITE)
+ else
cmd->targ_xfer_tag = 0xFFFFFFFF;
cmd->cmd_sn = be32_to_cpu(hdr->cmdsn);
cmd->exp_stat_sn = be32_to_cpu(hdr->exp_statsn);