[PATCH 3.4 054/107] target/iscsi: Fix double free of a TUR followed by a solicited NOPOUT

lizf
2016-03-16T08:10:41Z

From: Alexei Potashnik <alexei@purestorage.com>

3.4.111-rc1 review patch. If anyone has any objections, please let me know.

------------------

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>
[lizf: Backported to 3.4:
- adjust context
- leave the braces as it is]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
drivers/target/iscsi/iscsi_target.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 79665f3..963f383 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -981,7 +981,7 @@ done:
if (cmd->targ_xfer_tag == 0xFFFFFFFF)
cmd->targ_xfer_tag = conn->sess->targ_xfer_tag++;
spin_unlock_bh(&conn->sess->ttt_lock);
- } else if (hdr->flags & ISCSI_FLAG_CMD_WRITE)
+ } else
cmd->targ_xfer_tag = 0xFFFFFFFF;
cmd->cmd_sn = hdr->cmdsn;
cmd->exp_stat_sn = hdr->exp_statsn;
--
1.9.1