linux-stable.git/drivers/target, branch v3.16.48

target: Fix kref->refcount underflow in transport_cmd_finish_abort

2017-09-15T17:30:07+00:00

commit 73d4e580ccc5c3e05cea002f18111f66c9c07034 upstream.

This patch fixes a se_cmd->cmd_kref underflow during CMD_T_ABORTED
when a fabric driver drops it's second reference from below the
target_core_tmr.c based callers of transport_cmd_finish_abort().

Recently with the conversion of kref to refcount_t, this bug was
manifesting itself as:

[705519.601034] refcount_t: underflow; use-after-free.
[705519.604034] INFO: NMI handler (kgdb_nmi_handler) took too long to run: 20116.512 msecs
[705539.719111] ------------[ cut here ]------------
[705539.719117] WARNING: CPU: 3 PID: 26510 at lib/refcount.c:184 refcount_sub_and_test+0x33/0x51

Since the original kref atomic_t based kref_put() didn't check for
underflow and only invoked the final callback when zero was reached,
this bug did not manifest in practice since all se_cmd memory is
using preallocated tags.

To address this, go ahead and propigate the existing return from
transport_put_cmd() up via transport_cmd_finish_abort(), and
change transport_cmd_finish_abort() + core_tmr_handle_tas_abort()
callers to only do their local target_put_sess_cmd() if necessary.

Reported-by: Bart Van Assche 
Tested-by: Bart Van Assche 
Cc: Mike Christie 
Cc: Hannes Reinecke 
Cc: Christoph Hellwig 
Cc: Himanshu Madhani 
Cc: Sagi Grimberg 
Tested-by: Gary Guo 
Tested-by: Chu Yuan Lin 
Signed-off-by: Nicholas Bellinger 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

iscsi-target: Always wait for kthread_should_stop() before kthread exit

2017-09-15T17:29:53+00:00

commit 5e0cf5e6c43b9e19fc0284f69e5cd2b4a47523b0 upstream.

There are three timing problems in the kthread usages of iscsi_target_mod:

 - np_thread of struct iscsi_np
 - rx_thread and tx_thread of struct iscsi_conn

In iscsit_close_connection(), it calls

 send_sig(SIGINT, conn->tx_thread, 1);
 kthread_stop(conn->tx_thread);

In conn->tx_thread, which is iscsi_target_tx_thread(), when it receive
SIGINT the kthread will exit without checking the return value of
kthread_should_stop().

So if iscsi_target_tx_thread() exit right between send_sig(SIGINT...)
and kthread_stop(...), the kthread_stop() will try to stop an already
stopped kthread.

This is invalid according to the documentation of kthread_stop().

(Fix -ECONNRESET logout handling in iscsi_target_tx_thread and
 early iscsi_target_rx_thread failure case - nab)

Signed-off-by: Jiang Yi 
Signed-off-by: Nicholas Bellinger 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

iscsi-target: Fix initial login PDU asynchronous socket close OOPs

2017-09-15T17:29:53+00:00

commit 25cdda95fda78d22d44157da15aa7ea34be3c804 upstream.

This patch fixes a OOPs originally introduced by:

   commit bb048357dad6d604520c91586334c9c230366a14
   Author: Nicholas Bellinger 
   Date:   Thu Sep 5 14:54:04 2013 -0700

   iscsi-target: Add sk->sk_state_change to cleanup after TCP failure

which would trigger a NULL pointer dereference when a TCP connection
was closed asynchronously via iscsi_target_sk_state_change(), but only
when the initial PDU processing in iscsi_target_do_login() from iscsi_np
process context was blocked waiting for backend I/O to complete.

To address this issue, this patch makes the following changes.

First, it introduces some common helper functions used for checking
socket closing state, checking login_flags, and atomically checking
socket closing state + setting login_flags.

Second, it introduces a LOGIN_FLAGS_INITIAL_PDU bit to know when a TCP
connection has dropped via iscsi_target_sk_state_change(), but the
initial PDU processing within iscsi_target_do_login() in iscsi_np
context is still running.  For this case, it sets LOGIN_FLAGS_CLOSED,
but doesn't invoke schedule_delayed_work().

The original NULL pointer dereference case reported by MNC is now handled
by iscsi_target_do_login() doing a iscsi_target_sk_check_close() before
transitioning to FFP to determine when the socket has already closed,
or iscsi_target_start_negotiation() if the login needs to exchange
more PDUs (eg: iscsi_target_do_login returned 0) but the socket has
closed.  For both of these cases, the cleanup up of remaining connection
resources will occur in iscsi_target_start_negotiation() from iscsi_np
process context once the failure is detected.

Finally, to handle to case where iscsi_target_sk_state_change() is
called after the initial PDU procesing is complete, it now invokes
conn->login_work -> iscsi_target_do_login_rx() to perform cleanup once
existing iscsi_target_sk_check_close() checks detect connection failure.
For this case, the cleanup of remaining connection resources will occur
in iscsi_target_do_login_rx() from delayed workqueue process context
once the failure is detected.

Reported-by: Mike Christie 
Reviewed-by: Mike Christie 
Tested-by: Mike Christie 
Cc: Mike Christie 
Reported-by: Hannes Reinecke 
Cc: Hannes Reinecke 
Cc: Sagi Grimberg 
Cc: Varun Prakash 
Signed-off-by: Nicholas Bellinger 
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings

target/iscsi: Fix indentation in iscsi_target_start_negotiation()

2017-09-15T17:29:53+00:00

commit 1efaa949396b5d9e8d1e6edef7e97e9ce1a97319 upstream.

This patch avoids that smatch complains about inconsistent
indentation in iscsi_target_start_negotiation().

Signed-off-by: Bart Van Assche 
Reviewed-by: Hannes Reinecke 
Reviewed-by: Christoph Hellwig 
Cc: Nicholas A. Bellinger 
Signed-off-by: Nicholas Bellinger 
Signed-off-by: Ben Hutchings

iscsi-target: Fix early sk_data_ready LOGIN_FLAGS_READY race

2017-09-15T17:29:53+00:00

commit 8f0dfb3d8b1120c61f6e2cc3729290db10772b2d upstream.

There is a iscsi-target/tcp login race in LOGIN_FLAGS_READY
state assignment that can result in frequent errors during
iscsi discovery:

      "iSCSI Login negotiation failed."

To address this bug, move the initial LOGIN_FLAGS_READY
assignment ahead of iscsi_target_do_login() when handling
the initial iscsi_target_start_negotiation() request PDU
during connection login.

As iscsi_target_do_login_rx() work_struct callback is
clearing LOGIN_FLAGS_READ_ACTIVE after subsequent calls
to iscsi_target_do_login(), the early sk_data_ready
ahead of the first iscsi_target_do_login() expects
LOGIN_FLAGS_READY to also be set for the initial
login request PDU.

As reported by Maged, this was first obsered using an
MSFT initiator running across multiple VMWare host
virtual machines with iscsi-target/tcp.

Reported-by: Maged Mokhtar 
Tested-by: Maged Mokhtar 
Signed-off-by: Nicholas Bellinger 
Signed-off-by: Ben Hutchings

target/fileio: Fix zero-length READ and WRITE handling

2017-08-26T01:14:46+00:00

commit 59ac9c078141b8fd0186c0b18660a1b2c24e724e upstream.

This patch fixes zero-length READ and WRITE handling in target/FILEIO,
which was broken a long time back by:

Since:

  commit d81cb44726f050d7cf1be4afd9cb45d153b52066
  Author: Paolo Bonzini 
  Date:   Mon Sep 17 16:36:11 2012 -0700

      target: go through normal processing for all zero-length commands

which moved zero-length READ and WRITE completion out of target-core,
to doing submission into backend driver code.

To address this, go ahead and invoke target_complete_cmd() for any
non negative return value in fd_do_rw().

Signed-off-by: Bart Van Assche 
Reviewed-by: Hannes Reinecke 
Reviewed-by: Christoph Hellwig 
Cc: Andy Grover 
Cc: David Disseldorp 
Signed-off-by: Nicholas Bellinger 
Signed-off-by: Ben Hutchings

iscsi-target: Drop work-around for legacy GlobalSAN initiator

2017-07-18T17:40:29+00:00

commit 1c99de981f30b3e7868b8d20ce5479fa1c0fea46 upstream.

Once upon a time back in 2009, a work-around was added to support
the GlobalSAN iSCSI initiator v3.3 for MacOSX, which during login
did not propose nor respond to MaxBurstLength, FirstBurstLength,
DefaultTime2Wait and DefaultTime2Retain keys.

The work-around in iscsi_check_proposer_for_optional_reply()
allowed the missing keys to be proposed, but did not require
waiting for a response before moving to full feature phase
operation.  This allowed GlobalSAN v3.3 to work out-of-the
box, and for many years we didn't run into login interopt
issues with any other initiators..

Until recently, when Martin tried a QLogic 57840S iSCSI Offload
HBA on Windows 2016 which completed login, but subsequently
failed with:

    Got unknown iSCSI OpCode: 0x43

The issue was QLogic MSFT side did not propose DefaultTime2Wait +
DefaultTime2Retain, so LIO proposes them itself, and immediately
transitions to full feature phase because of the GlobalSAN hack.
However, the QLogic MSFT side still attempts to respond to
DefaultTime2Retain + DefaultTime2Wait, even though LIO has set
ISCSI_FLAG_LOGIN_NEXT_STAGE3 + ISCSI_FLAG_LOGIN_TRANSIT
in last login response.

So while the QLogic MSFT side should have been proposing these
two keys to start, it was doing the correct thing per RFC-3720
attempting to respond to proposed keys before transitioning to
full feature phase.

All that said, recent versions of GlobalSAN iSCSI (v5.3.0.541)
does correctly propose the four keys during login, making the
original work-around moot.

So in order to allow QLogic MSFT to run unmodified as-is, go
ahead and drop this long standing work-around.

Reported-by: Martin Svec 
Cc: Martin Svec 
Cc: Himanshu Madhani 
Cc: Arun Easi 
Signed-off-by: Nicholas Bellinger 
Signed-off-by: Ben Hutchings

iscsi-target: Fix TMR reference leak during session shutdown

2017-07-18T17:40:26+00:00

commit efb2ea770bb3b0f40007530bc8b0c22f36e1c5eb upstream.

This patch fixes a iscsi-target specific TMR reference leak
during session shutdown, that could occur when a TMR was
quiesced before the hand-off back to iscsi-target code
via transport_cmd_check_stop_to_fabric().

The reference leak happens because iscsit_free_cmd() was
incorrectly skipping the final target_put_sess_cmd() for
TMRs when transport_generic_free_cmd() returned zero because
the se_cmd->cmd_kref did not reach zero, due to the missing
se_cmd assignment in original code.

The result was iscsi_cmd and it's associated se_cmd memory
would be freed once se_sess->sess_cmd_map where released,
but the associated se_tmr_req was leaked and remained part
of se_device->dev_tmr_list.

This bug would manfiest itself as kernel paging request
OOPsen in core_tmr_lun_reset(), when a left-over se_tmr_req
attempted to dereference it's se_cmd pointer that had
already been released during normal session shutdown.

To address this bug, go ahead and treat ISCSI_OP_SCSI_CMD
and ISCSI_OP_SCSI_TMFUNC the same when there is an extra
se_cmd->cmd_kref to drop in iscsit_free_cmd(), and use
op_scsi to signal __iscsit_free_cmd() when the former
needs to clear any further iscsi related I/O state.

Reported-by: Rob Millner 
Cc: Rob Millner 
Reported-by: Chu Yuan Lin 
Cc: Chu Yuan Lin 
Tested-by: Chu Yuan Lin 
Signed-off-by: Nicholas Bellinger 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

target: Fix VERIFY_16 handling in sbc_parse_cdb

2017-07-18T17:40:09+00:00

commit 13603685c1f12c67a7a2427f00b63f39a2b6f7c9 upstream.

As reported by Max, the Windows 2008 R2 chkdsk utility expects
VERIFY_16 to be supported, and does not handle the returned
CHECK_CONDITION properly, resulting in an infinite loop.

The kernel will log huge amounts of this error:

kernel: TARGET_CORE[iSCSI]: Unsupported SCSI Opcode 0x8f, sending
CHECK_CONDITION.

Signed-off-by: Max Lohrmann 
Signed-off-by: Nicholas Bellinger 
Signed-off-by: Ben Hutchings

target/pscsi: Fix TYPE_TAPE + TYPE_MEDIMUM_CHANGER export

2017-07-18T17:40:08+00:00

commit a04e54f2c35823ca32d56afcd5cea5b783e2f51a upstream.

The following fixes a divide by zero OOPs with TYPE_TAPE
due to pscsi_tape_read_blocksize() failing causing a zero
sd->sector_size being propigated up via dev_attrib.hw_block_size.

It also fixes another long-standing bug where TYPE_TAPE and
TYPE_MEDIMUM_CHANGER where using pscsi_create_type_other(),
which does not call scsi_device_get() to take the device
reference.  Instead, rename pscsi_create_type_rom() to
pscsi_create_type_nondisk() and use it for all cases.

Finally, also drop a dump_stack() in pscsi_get_blocks() for
non TYPE_DISK, which in modern target-core can get invoked
via target_sense_desc_format() during CHECK_CONDITION.

Reported-by: Malcolm Haak 
Signed-off-by: Nicholas Bellinger 
[bwh: Backported to 3.16:
 - Deleted log format is slightly different
 - Cast Scsi_Host::max_sectors from unsigned short to unsigned int, to avoid
   a warning about differing types in min_not_zero()]
Signed-off-by: Ben Hutchings