linux-stable.git/fs/dlm/midcomms.c, branch linux-5.15.y

fs: dlm: fix use after free in midcomms commit

2026-06-01T15:35:09+00:00

[ Upstream commit 724b6bab0d75f1dc01fdfbf7fe8d4217a5cb90ba ]

While working on processing dlm message in softirq context I experienced
the following KASAN use-after-free warning:

[  151.760477] ==================================================================
[  151.761803] BUG: KASAN: use-after-free in dlm_midcomms_commit_mhandle+0x19d/0x4b0
[  151.763414] Read of size 4 at addr ffff88811a980c60 by task lock_torture/1347

[  151.765284] CPU: 7 PID: 1347 Comm: lock_torture Not tainted 6.1.0-rc4+ #2828
[  151.766778] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-3.module+el8.7.0+16134+e5908aa2 04/01/2014
[  151.768726] Call Trace:
[  151.769277]  
[  151.769748]  dump_stack_lvl+0x5b/0x86
[  151.770556]  print_report+0x180/0x4c8
[  151.771378]  ? kasan_complete_mode_report_info+0x7c/0x1e0
[  151.772241]  ? dlm_midcomms_commit_mhandle+0x19d/0x4b0
[  151.773069]  kasan_report+0x93/0x1a0
[  151.773668]  ? dlm_midcomms_commit_mhandle+0x19d/0x4b0
[  151.774514]  __asan_load4+0x7e/0xa0
[  151.775089]  dlm_midcomms_commit_mhandle+0x19d/0x4b0
[  151.775890]  ? create_message.isra.29.constprop.64+0x57/0xc0
[  151.776770]  send_common+0x19f/0x1b0
[  151.777342]  ? remove_from_waiters+0x60/0x60
[  151.778017]  ? lock_downgrade+0x410/0x410
[  151.778648]  ? __this_cpu_preempt_check+0x13/0x20
[  151.779421]  ? rcu_lockdep_current_cpu_online+0x88/0xc0
[  151.780292]  _convert_lock+0x46/0x150
[  151.780893]  convert_lock+0x7b/0xc0
[  151.781459]  dlm_lock+0x3ac/0x580
[  151.781993]  ? 0xffffffffc0540000
[  151.782522]  ? torture_stop+0x120/0x120 [dlm_locktorture]
[  151.783379]  ? dlm_scan_rsbs+0xa70/0xa70
[  151.784003]  ? preempt_count_sub+0xd6/0x130
[  151.784661]  ? is_module_address+0x47/0x70
[  151.785309]  ? torture_stop+0x120/0x120 [dlm_locktorture]
[  151.786166]  ? 0xffffffffc0540000
[  151.786693]  ? lockdep_init_map_type+0xc3/0x360
[  151.787414]  ? 0xffffffffc0540000
[  151.787947]  torture_dlm_lock_sync.isra.3+0xe9/0x150 [dlm_locktorture]
[  151.789004]  ? torture_stop+0x120/0x120 [dlm_locktorture]
[  151.789858]  ? 0xffffffffc0540000
[  151.790392]  ? lock_torture_cleanup+0x20/0x20 [dlm_locktorture]
[  151.791347]  ? delay_tsc+0x94/0xc0
[  151.791898]  torture_ex_iter+0xc3/0xea [dlm_locktorture]
[  151.792735]  ? torture_start+0x30/0x30 [dlm_locktorture]
[  151.793606]  lock_torture+0x177/0x270 [dlm_locktorture]
[  151.794448]  ? torture_dlm_lock_sync.isra.3+0x150/0x150 [dlm_locktorture]
[  151.795539]  ? lock_torture_stats+0x80/0x80 [dlm_locktorture]
[  151.796476]  ? do_raw_spin_lock+0x11e/0x1e0
[  151.797152]  ? mark_held_locks+0x34/0xb0
[  151.797784]  ? _raw_spin_unlock_irqrestore+0x30/0x70
[  151.798581]  ? __kthread_parkme+0x79/0x110
[  151.799246]  ? trace_preempt_on+0x2a/0xf0
[  151.799902]  ? __kthread_parkme+0x79/0x110
[  151.800579]  ? preempt_count_sub+0xd6/0x130
[  151.801271]  ? __kasan_check_read+0x11/0x20
[  151.801963]  ? __kthread_parkme+0xec/0x110
[  151.802630]  ? lock_torture_stats+0x80/0x80 [dlm_locktorture]
[  151.803569]  kthread+0x192/0x1d0
[  151.804104]  ? kthread_complete_and_exit+0x30/0x30
[  151.804881]  ret_from_fork+0x1f/0x30
[  151.805480]  

[  151.806111] Allocated by task 1347:
[  151.806681]  kasan_save_stack+0x26/0x50
[  151.807308]  kasan_set_track+0x25/0x30
[  151.807920]  kasan_save_alloc_info+0x1e/0x30
[  151.808609]  __kasan_slab_alloc+0x63/0x80
[  151.809263]  kmem_cache_alloc+0x1ad/0x830
[  151.809916]  dlm_allocate_mhandle+0x17/0x20
[  151.810590]  dlm_midcomms_get_mhandle+0x96/0x260
[  151.811344]  _create_message+0x95/0x180
[  151.811994]  create_message.isra.29.constprop.64+0x57/0xc0
[  151.812880]  send_common+0x129/0x1b0
[  151.813467]  _convert_lock+0x46/0x150
[  151.814074]  convert_lock+0x7b/0xc0
[  151.814648]  dlm_lock+0x3ac/0x580
[  151.815199]  torture_dlm_lock_sync.isra.3+0xe9/0x150 [dlm_locktorture]
[  151.816258]  torture_ex_iter+0xc3/0xea [dlm_locktorture]
[  151.817129]  lock_torture+0x177/0x270 [dlm_locktorture]
[  151.817986]  kthread+0x192/0x1d0
[  151.818518]  ret_from_fork+0x1f/0x30

[  151.819369] Freed by task 1336:
[  151.819890]  kasan_save_stack+0x26/0x50
[  151.820514]  kasan_set_track+0x25/0x30
[  151.821128]  kasan_save_free_info+0x2e/0x50
[  151.821812]  __kasan_slab_free+0x107/0x1a0
[  151.822483]  kmem_cache_free+0x204/0x5e0
[  151.823152]  dlm_free_mhandle+0x18/0x20
[  151.823781]  dlm_mhandle_release+0x2e/0x40
[  151.824454]  rcu_core+0x583/0x1330
[  151.825047]  rcu_core_si+0xe/0x20
[  151.825594]  __do_softirq+0xf4/0x5c2

[  151.826450] Last potentially related work creation:
[  151.827238]  kasan_save_stack+0x26/0x50
[  151.827870]  __kasan_record_aux_stack+0xa2/0xc0
[  151.828609]  kasan_record_aux_stack_noalloc+0xb/0x20
[  151.829415]  call_rcu+0x4c/0x760
[  151.829954]  dlm_mhandle_delete+0x97/0xb0
[  151.830718]  dlm_process_incoming_buffer+0x2fc/0xb30
[  151.831524]  process_dlm_messages+0x16e/0x470
[  151.832245]  process_one_work+0x505/0xa10
[  151.832905]  worker_thread+0x67/0x650
[  151.833507]  kthread+0x192/0x1d0
[  151.834046]  ret_from_fork+0x1f/0x30

[  151.834900] The buggy address belongs to the object at ffff88811a980c30
                which belongs to the cache dlm_mhandle of size 88
[  151.836894] The buggy address is located 48 bytes inside of
                88-byte region [ffff88811a980c30, ffff88811a980c88)

[  151.839007] The buggy address belongs to the physical page:
[  151.839904] page:0000000076cf5d62 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11a980
[  151.841378] flags: 0x8000000000000200(slab|zone=2)
[  151.842141] raw: 8000000000000200 0000000000000000 dead000000000122 ffff8881089b43c0
[  151.843401] raw: 0000000000000000 0000000000220022 00000001ffffffff 0000000000000000
[  151.844640] page dumped because: kasan: bad access detected

[  151.845822] Memory state around the buggy address:
[  151.846602]  ffff88811a980b00: fb fb fb fb fc fc fc fc fa fb fb fb fb fb fb fb
[  151.847761]  ffff88811a980b80: fb fb fb fc fc fc fc fa fb fb fb fb fb fb fb fb
[  151.848921] >ffff88811a980c00: fb fb fc fc fc fc fa fb fb fb fb fb fb fb fb fb
[  151.850076]                                                        ^
[  151.851085]  ffff88811a980c80: fb fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb
[  151.852269]  ffff88811a980d00: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fc
[  151.853428] ==================================================================
[  151.855618] Disabling lock debugging due to kernel taint

It is accessing a mhandle in dlm_midcomms_commit_mhandle() and the mhandle
was freed by a call_rcu() call in dlm_process_incoming_buffer(),
dlm_mhandle_delete(). It looks like it was freed because an ack of
this message was received. There is a short race between committing the
dlm message to be transmitted and getting an ack back. If the ack is
faster than returning from dlm_midcomms_commit_msg_3_2(), then we run
into a use-after free because we still need to reference the mhandle when
calling srcu_read_unlock().

To avoid that, we don't allow that mhandle to be freed between
dlm_midcomms_commit_msg_3_2() and srcu_read_unlock() by using rcu read
lock. We can do that because mhandle is protected by rcu handling.

Cc: stable@vger.kernel.org
Fixes: 489d8e559c65 ("fs: dlm: add reliable connection if reconnect")
Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland 
[ Minor conflict resolved. ]
Signed-off-by: Jianqiang kang 
Signed-off-by: Greg Kroah-Hartman

fs: dlm: add midcomms init/start functions

2023-03-17T07:48:49+00:00

[ Upstream commit 8b0188b0d60b6f6183b48380bac49fe080c5ded9 ]

This patch introduces leftovers of init, start, stop and exit
functionality. The dlm application layer should always call the midcomms
layer which getting aware of such event and redirect it to the lowcomms
layer. Some functionality which is currently handled inside the start
functionality of midcomms and lowcomms should be handled in the init
functionality as it only need to be initialized once when dlm is loaded.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland 
Stable-dep-of: aad633dc0cf9 ("fs: dlm: start midcomms before scand")
Signed-off-by: Sasha Levin

fs: dlm: send FIN ack back in right cases

2023-03-10T08:39:58+00:00

commit 00908b3388255fc1d3782b744d07f327712f401f upstream.

This patch moves to send a ack back for receiving a FIN message only
when we are in valid states. In other cases and there might be a sender
waiting for a ack we just let it timeout at the senders time and
hopefully all other cleanups will remove the FIN message on their
sending queue. As an example we should never send out an ACK being in
LAST_ACK state or we cannot assume a working socket communication when
we are in CLOSED state.

Cc: stable@vger.kernel.org
Fixes: 489d8e559c65 ("fs: dlm: add reliable connection if reconnect")
Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland 
Signed-off-by: Greg Kroah-Hartman

fs: dlm: move sending fin message into state change handling

2023-03-10T08:39:58+00:00

commit a58496361802070996f9bd76e941d109c4a85ebd upstream.

This patch moves the send fin handling, which should appear in a specific
state change, into the state change handling while the per node
state_lock is held. I experienced issues with other messages because
we changed the state and a fin message was sent out in a different state.

Cc: stable@vger.kernel.org
Fixes: 489d8e559c65 ("fs: dlm: add reliable connection if reconnect")
Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland 
Signed-off-by: Greg Kroah-Hartman

fs: dlm: don't set stop rx flag after node reset

2023-03-10T08:39:58+00:00

commit 15c63db8e86a72e0d5cfb9bf0cd1870e39a3e5fe upstream.

Similar to the stop tx flag, the rx flag should warn about a dlm message
being received at DLM_FIN state change, when we are assuming no other
dlm application messages. If we receive a FIN message and we are in the
state DLM_FIN_WAIT2 we call midcomms_node_reset() which puts the
midcomms node into DLM_CLOSED state. Afterwards we should not set the
DLM_NODE_FLAG_STOP_RX flag any more.  This patch changes the setting
DLM_NODE_FLAG_STOP_RX in those state changes when we receive a FIN
message and we assume there will be no other dlm application messages
received until we hit DLM_CLOSED state.

Cc: stable@vger.kernel.org
Fixes: 489d8e559c65 ("fs: dlm: add reliable connection if reconnect")
Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland 
Signed-off-by: Greg Kroah-Hartman

fs: dlm: implement delayed ack handling

2021-08-19T16:33:03+00:00

This patch changes that we don't ack each message. Lowcomms will take
care about to send an ack back after a bulk of messages was processed.
Currently it's only when the whole receive buffer was processed, there
might better positions to send an ack back but only the lowcomms
implementation know when there are more data to receive. This patch has
also disadvantages that we might retransmit more on errors, however this
is a very rare case.

Tested with make_panic on gfs2 with three nodes by running:

trace-cmd record -p function -l 'dlm_send_ack' sleep 100

and

trace-cmd report | wc -l

Before patch:
- 20548
- 21376
- 21398

After patch:
- 18338
- 20679
- 19949

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: invalid buffer access in lookup error

2021-06-11T17:44:47+00:00

This patch will evaluate the message length if a dlm opts header can fit
in before accessing it if a node lookup fails. The invalid sequence
error means that the version detection failed and an unexpected message
arrived. For debugging such situation the type of arrived message is
important to know.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: fix race in mhandle deletion

2021-06-11T17:44:47+00:00

This patch fixes a race between mhandle deletion in case of receiving an
acknowledge and flush of all pending mhandle in cases of an timeout or
resetting node states.

Fixes: 489d8e559c65 ("fs: dlm: add reliable connection if reconnect")
Reported-by: Guillaume Nault 
Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: rename socket and app buffer defines

2021-06-02T16:53:04+00:00

This patch renames DEFAULT_BUFFER_SIZE to DLM_MAX_SOCKET_BUFSIZE and
LOWCOMMS_MAX_TX_BUFFER_LEN to DLM_MAX_APP_BUFSIZE as they are proper
names to define what's behind those values. The DLM_MAX_SOCKET_BUFSIZE
defines the maximum size of buffer which can be handled on socket layer,
the DLM_MAX_APP_BUFSIZE defines the maximum size of buffer which can be
handled by the DLM application layer.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: Fix spelling mistake "stucked" -> "stuck"

2021-05-26T14:49:04+00:00

There are spelling mistake in log messages. Fix these.

Signed-off-by: Colin Ian King 
Signed-off-by: David Teigland