[ Upstream commit e546128291f8d688dcb931827e2efd2aa6c0734d ]

snd_seq_fifo_resize() still needs to publish the replacement pool
before it waits for FIFO users. A blocking snd_seq_read() holds
f->use_lock while it sleeps, so concurrent senders must be able to
queue to the new pool and wake that reader instead of failing against a
closing old pool.

However, snd_seq_fifo_event_in() duplicates an event before it takes
f->lock, and snd_seq_read() can dequeue a cell and later call
snd_seq_fifo_cell_putback() if copy_to_user() or
snd_seq_expand_var_event() fails. If resize swaps f->pool and detaches
oldhead in between, either path can relink an old-pool cell after the
snapshot. That stale cell sits outside the drained oldhead list, keeps
oldpool->counter elevated, and can leave snd_seq_pool_delete() waiting
for the retired pool to drain.

Keep the existing swap-before-wait ordering in snd_seq_fifo_resize(),
but reject stale cells before any FIFO relink. Revalidate event-in cells
under f->lock and retry them against the published replacement pool, and
free stale putback cells instead of linking them back into the FIFO.

The buggy scenario involves two paths, with each column showing the
order within that path:

resize path:                    relink path:
1. Allocate newpool.             1. Take f->use_lock.
2. Swap f->pool to newpool and   2. Duplicate or dequeue an old-pool
   detach oldhead.                  cell before oldpool closes.
3. Mark oldpool closing and      3. Reach a later relink point after
   wait for FIFO users.             resize published newpool.
4. Free oldhead and delete       4. Relink the old-pool cell after
   oldpool.                         resize detached oldhead.
                                 5. Drop f->use_lock.

The reproducer reports a resize ioctl blocked in the expected pool
teardown path:

signal: resize iteration=98 target_pool=4 exceeded 250ms
        (elapsed=251ms)
diagnostic: resize_tid=651 wchan=snd_seq_pool_done
diagnostic: resize_tid=651 stack=
  snd_seq_pool_done+0x5b/0x140
  snd_seq_pool_delete+0x7a/0x90
  snd_seq_fifo_resize+0x193/0x1e0
  snd_seq_ioctl_set_client_pool+0x214/0x260
  snd_seq_ioctl+0x119/0x540
  __x64_sys_ioctl+0xd1/0x120
  do_syscall_64+0xbb/0x2f0
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

A second run with larger pools hit the same target path:

signal: resize iteration=32 target_pool=64 exceeded 250ms
        (elapsed=251ms)
diagnostic: resize_tid=663 wchan=snd_seq_pool_done
diagnostic: resize_tid=663 stack=
  snd_seq_pool_done+0x5b/0x140
  snd_seq_pool_delete+0x7a/0x90
  snd_seq_fifo_resize+0x193/0x1e0
  snd_seq_ioctl_set_client_pool+0x214/0x260
  snd_seq_ioctl+0x119/0x540
  __x64_sys_ioctl+0xd1/0x120
  do_syscall_64+0xbb/0x2f0
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fixes: 2d7d54002e39 ("ALSA: seq: Fix race during FIFO resize")

Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Link: https://patch.msgid.link/20260614004801.3507773-2-zzzccc427@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 49ce92d207820f588b0406add82f053decfbe5d9 ]

snd_seq_oss_readq_clear() resets qlen, head, and tail without
q->lock even though the normal reader and producer paths serialize the
same ring state under that spinlock. A reset can therefore race
snd_seq_oss_readq_free() or snd_seq_oss_readq_put_event() and leave
stale records in the queue, drop freshly queued ones, or report the
wrong readiness after wakeup. KCSAN reports a data race between
snd_seq_oss_readq_clear() and snd_seq_oss_readq_free().

Take q->lock while clearing the ring and resetting input_time. Factor
the enqueue logic into a caller-locked helper so
snd_seq_oss_readq_put_timestamp() updates its suppression state under
the same lock instead of racing the reset path.

The buggy scenario involves two paths, with each column showing the
order within that path:

reset path:                      locked readq updater:
1. snd_seq_oss_reset() or        1. A reader or callback producer
   release reaches                  takes q->lock on the same queue.
   snd_seq_oss_readq_clear().
2. snd_seq_oss_readq_clear()     2. The updater tests or modifies
   resets qlen, head, tail,         qlen, head, and tail.
   and input_time.
3. snd_seq_oss_readq_clear()     3. The updater completes its
   wakes sleepers on                read-modify-write sequence.
   q->midi_sleep.
4. Without q->lock, the reset    4. The resulting ring state drives
   can overlap the locked           later reads and readiness.
   update.

KCSAN reports:

BUG: KCSAN: data-race in snd_seq_oss_readq_clear /
snd_seq_oss_readq_free

write to 0xffff8881069fe608 of 4 bytes by task 120516 on cpu 0:
  snd_seq_oss_readq_free+0x6c/0x80
  snd_seq_oss_read+0xcb/0x250
  odev_read+0x38/0x60
  vfs_read+0xff/0x600
  ksys_read+0xb4/0x140
  __x64_sys_read+0x46/0x60
  do_syscall_64+0xbb/0x2f0
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881069fe608 of 4 bytes by task 120517 on cpu 1:
  snd_seq_oss_readq_clear+0x1f/0x90
  snd_seq_oss_reset+0xa7/0xf0
  snd_seq_oss_ioctl+0x6f6/0x7e0
  odev_ioctl+0x56/0xc0
  __x64_sys_ioctl+0xd1/0x120
  do_syscall_64+0xbb/0x2f0
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000001 -> 0x00000000

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")

Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Link: https://patch.msgid.link/20260614004801.3507773-1-zzzccc427@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit efc86691e4d8083d9e380ea95042c2cf679f65fd ]

The comment above bounce_error_event() documents that user clients
should receive SNDRV_SEQ_EVENT_BOUNCE with the original event embedded
as variable-length data, while kernel clients should receive
SNDRV_SEQ_EVENT_KERNEL_ERROR with a quoted kernel pointer.

However, the implementation unconditionally uses
SNDRV_SEQ_EVENT_KERNEL_ERROR with data.quote.event set to the raw
struct snd_seq_event pointer for all clients.  When a bounce error
event is delivered to a USER_CLIENT via snd_seq_read(), the kernel
heap address in data.quote.event is exposed to userspace through
copy_to_user() in the fixed-length branch.

This is a distinct leak path from the one addressed by commit
705dd6dcbc0e ("ALSA: seq: Clear variable event pointer on read"),
which sanitizes data.ext.ptr in the variable-length branch of
snd_seq_read().  The bounce_error_event() leak uses fixed-length
events that take the else branch where no sanitization occurs.

Differentiate the bounce event by client type.  For USER_CLIENT,
send SNDRV_SEQ_EVENT_BOUNCE with SNDRV_SEQ_EVENT_LENGTH_VARIABLE
and data.ext pointing to the original event.  The variable-length
path in snd_seq_event_dup() copies the event data into chained
cells, and snd_seq_expand_var_event() copies only the content --
never the pointer -- to userspace.  For KERNEL_CLIENT, keep the
existing SNDRV_SEQ_EVENT_KERNEL_ERROR behavior with the quoted
pointer.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: HanQuan <eilaimemedsnaimel@gmail.com>
Link: https://patch.msgid.link/20260612103222.2528305-1-eilaimemedsnaimel@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 705dd6dcbc0ea87351c660c1a6443f85f1001c76 ]

snd_seq_read() copies a queued variable-length event header to userspace
before expanding the payload. Queued variable-length events use
SNDRV_SEQ_EXT_CHAINED internally, and data.ext.ptr points at the first
extension cell.

The read side strips SNDRV_SEQ_EXT_* bits from data.ext.len before the
copy, but it leaves data.ext.ptr untouched. A userspace sequencer client
can therefore write a direct variable event to itself and read back the
extension-cell kernel address from the returned header.

Clear the temporary header pointer before copy_to_user(). The original
queued event remains unchanged and is still passed to
snd_seq_expand_var_event(), so payload expansion keeps using the
internal chain.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kyle Zeng <kylebot@openai.com>
Link: https://patch.msgid.link/20260607004129.61345-1-kylebot@openai.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 2b7bd6f548292aec92a386deebe62324d21d62a9 ]

snd_seq_expand_var_event_at() clamps the number of bytes to copy to the
remaining variable-event length, but passes the original buffer size to
expand_var_event().

For SNDRV_SEQ_EXT_USRPTR events, expand_var_event() copies exactly the
size argument from userspace.  On the final chunk, when the remaining
event data is shorter than the caller's buffer, this can read past the
declared event data and can spuriously fail with -EFAULT if the extra
bytes cross an unmapped page.

Pass the clamped length instead.  The chained and kernel-backed paths
already reclamp in dump_var_event(), but the user-pointer path handles
the size directly.

Fixes: ea46f79709b6 ("ALSA: seq: Add snd_seq_expand_var_event_at() helper")
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Link: https://patch.msgid.link/20260606040913.230213-1-sammiee5311@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit ef7607ab1c8adc6258fb1b27d08e26aecdc18a58 ]

event_process_midi() borrows msynth->output_rfile.output and then
passes the substream to dump_midi() and snd_rawmidi_kernel_write()
without synchronizing with the output open/close transition.
midisynth_use() also publishes output_rfile before
snd_rawmidi_output_params() has finished.

The last midisynth_unuse() can therefore release the same rawmidi file
and free substream->runtime before snd_rawmidi_kernel_write1() takes
its runtime buffer reference. That leaves the event_input path using a
stale substream or runtime and can end in a NULL-deref or use-after-free.

Fix this with two pieces of synchronization. Keep a short IRQ-safe
spinlock only for publishing or clearing output_rfile and for pairing
the output snapshot with an snd_use_lock_t reference. Once
event_process_midi() has taken that in-flight reference, it drops the
spinlock before calling snd_seq_dump_var_event(), dump_midi(), or
snd_rawmidi_kernel_write(). midisynth_unuse() now detaches the visible
rawmidi file under the same spinlock, waits for the in-flight writers
to drain, and only then drains and releases the saved file.
midisynth_use() likewise opens into a local snd_rawmidi_file and
publishes it only after snd_rawmidi_output_params() succeeds.

The buggy scenario involves two paths, with each column showing the
order within that path:

event_input path:                     last unuse path:
1. event_process_midi() snapshots    1. midisynth_unuse() starts
   output_rfile.output.                 tearing down output_rfile.
2. dump_midi() reaches               2. snd_rawmidi_kernel_release()
   snd_rawmidi_kernel_write()           closes the output file.
   before runtime is pinned.         3. close_substream() frees
3. The callback keeps using             substream->runtime.
   the borrowed substream.

Validation reproduced this kernel report:
KASAN null-ptr-deref in snd_rawmidi_kernel_write1+0x56/0x360
RIP: 0033:0x7fde7dd0837f
RIP: 0010:snd_rawmidi_kernel_write1+0x56/0x360

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Assisted-by: Codex:gpt-5.5
Signed-off-by: Zhang Cen <rollkingzzc@gmail.com>
Link: https://patch.msgid.link/20260527062948.3614025-1-rollkingzzc@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 7c349b4f2a603202fb8c363bd2774a22ac2fddf3 ]

The OSS sequencer processes the input MIDI bytes into a sequencer
event to be dispatched later (in snd_seq_oss_midi_putc() called from
snd_seq_oss_process_event()).  When it's a SysEx data, the event
record contains data.ext.ptr pointer to the original SysEx bytes, and
the referred data is copied into the pool afterwards at dispatching.
The problem is that, if the sequencer port gets closed concurrently
before the dispatch, the OSS sequencer core also releases the
resources (in snd_seq_oss_midi_check_exit_port()), while the pending
event may hold a stale pointer, eventually leading to a UAF at a later
dispatch.

Fortunately, there is already a refcounting mechanism (snd_use_lock_t)
for the OSS MIDI device access, and for addressing the issue above, we
just need to extend the refcount until the event gets dispatched.

This patch extends snd_seq_oss_process_event() to give back the
refcount object, which is in turn released after calling the sequencer
dispatcher with the given event in the caller side.

According to the original report, KASAN report as below:

KASAN slab-use-after-free in snd_seq_event_dup+0x40c/0x470
RIP: 0033:0x7f2cb66a6340
Read of size 6
Call trace:
  dump_stack_lvl+0x73/0xb0 (?:?)
  print_report+0xd1/0x650 (?:?)
  srso_alias_return_thunk+0x5/0xfbef5 (?:?)
  __virt_addr_valid+0x1a7/0x340 (?:?)
  kasan_complete_mode_report_info+0x64/0x200 (?:?)
  kasan_report+0xf7/0x130 (?:?)
  snd_seq_event_dup+0x40c/0x470 (?:?)
  kasan_check_range+0x10c/0x1c0 (?:?)
  __asan_memcpy+0x27/0x70 (?:?)
  snd_seq_event_dup+0x9/0x470 (?:?)
  snd_seq_client_enqueue_event+0x139/0x240 (?:?)
  _raw_spin_unlock_irqrestore+0x4b/0x60 (?:?)
  snd_seq_kernel_client_enqueue+0x102/0x120 (?:?)
  snd_seq_oss_write+0x416/0x4e0 (?:?)
  apparmor_file_permission+0x20/0x30 (?:?)
  odev_write+0x3b/0x60 (?:?)
  vfs_write+0x1ce/0x850 (?:?)
  lock_release+0xc8/0x2a0 (?:?)
  __kasan_check_write+0x18/0x20 (?:?)
  __mutex_unlock_slowpath+0x129/0x510 (?:?)
  ksys_write+0xe1/0x180 (?:?)
  mutex_unlock+0x16/0x20 (?:?)
  odev_ioctl+0x65/0xc0 (?:?)
  __x64_sys_write+0x46/0x60 (?:?)
  x64_sys_call+0x7d/0x20d0 (?:?)
  do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87)
  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-and-tested-by: Zhang Cen <rollkingzzc@gmail.com>
Closes: https://lore.kernel.org/20260521233900.478153-1-rollkingzzc@gmail.com
Link: https://patch.msgid.link/20260526152843.617503-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

commit 435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4 upstream.

snd_seq_event_dup() copies an incoming event into a pool cell and, in
the UMP-enabled build, clears the trailing cell->ump.raw.extra word that
the memcpy() did not cover.  The guard deciding whether to clear it
compares the copied size against sizeof(cell->event):

	memcpy(&cell->ump, event, size);
	if (size < sizeof(cell->event))
		cell->ump.raw.extra = 0;

For a legacy (non-UMP) event, size == sizeof(struct snd_seq_event) ==
sizeof(cell->event), so the condition is false and the extra word keeps
stale data.  The cell pool is allocated with kvmalloc() (not zeroed) and
cells are reused via a free list, so that word holds uninitialised heap
or leftover event data.

When such a cell is delivered to a UMP client (client->midi_version > 0)
that set SNDRV_SEQ_FILTER_NO_CONVERT -- so the legacy event reaches it
unconverted -- snd_seq_read() reads it out as the larger struct
snd_seq_ump_event and copies the stale word to user space, a 4-byte
kernel heap infoleak to an unprivileged /dev/snd/seq client.

Compare against sizeof(cell->ump) instead, so the trailing word is zeroed
for every event shorter than the UMP cell.

Fixes: 46397622a3fa ("ALSA: seq: Add UMP support")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Link: https://patch.msgid.link/20260623233841.853326-1-sammiee5311@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 2b5ff4db5d7aa5b981d966df02e687f79ad7b311 ]

The dummy sequencer port forwards events by copying an incoming
struct snd_seq_event into a stack temporary, rewriting source and
destination, and dispatching the temporary to subscribers. That legacy
event storage is smaller than struct snd_seq_ump_event.

When a UMP event reaches the dummy client, the copy leaves the UMP flag
set but only provides legacy-sized stack storage. The subscriber
delivery path then uses snd_seq_event_packet_size() and copies a
UMP-sized packet from that stack object, reading past the end of the
temporary.

Use the existing union __snd_seq_event storage and copy the packet size
reported for the incoming event before rewriting the common routing
fields. This preserves the full UMP packet for UMP events while keeping
legacy event handling unchanged.

Fixes: 32cb23a0f911 ("ALSA: seq: dummy: Allow UMP conversion")
Signed-off-by: Kyle Zeng <kylebot@openai.com>
Link: https://patch.msgid.link/20260605080204.32045-1-kylebot@openai.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 60a1969fae6209644698fca91c185d153674f631 ]

seq_ump_process_event() borrows client->out_rfile.output without
synchronizing with the first-open and last-close transition in
seq_ump_client_open() and seq_ump_client_close().

The last output unuse can therefore drop opened[STR_OUT] to zero and
release the rawmidi file while an in-flight event_input callback is still
inside snd_rawmidi_kernel_write(). That leaves the rawmidi substream
runtime exposed to teardown before the write path has taken its own
buffer reference.

Add a per-client rwlock for the event_input-visible output file. Publish
a newly opened output file under the write side, and hold the read side
from the output lookup through snd_rawmidi_kernel_write(). The last
output close copies and clears the visible output file under the write
side, then drops the lock and releases the saved rawmidi file. Use
IRQ-safe rwlock guards because event_input can also be reached from
atomic sequencer delivery.

The buggy scenario involves two paths, with each column showing the
order within that path:

path A label: event_input path         path B label: last unuse path
1. seq_ump_process_event() reads       1. seq_ump_client_close()
   client->out_rfile.output.              drops opened[STR_OUT] to zero.
2. snd_rawmidi_kernel_write1()         2. snd_rawmidi_kernel_release()
   has not yet pinned runtime.            closes the output file.
3. The writer continues using          3. close_substream() frees
   the borrowed substream.                substream->runtime.

This keeps the output substream and runtime alive for the full
event_input write while keeping rawmidi release outside the rwlock.

KASAN reproduced this as a slab-use-after-free in
snd_rawmidi_kernel_write1(), with allocation through
seq_ump_use()/snd_seq_port_connect() and free through
seq_ump_unuse()/snd_seq_port_disconnect().

Suggested-by: Takashi Iwai <tiwai@suse.de>

Validation reproduced this kernel report:
KASAN slab-use-after-free in snd_rawmidi_kernel_write1+0x9d/0x400
RIP: 0033:0x7f5528af837f
Read of size 8
Call trace:
  dump_stack_lvl+0x73/0xb0 (?:?)
  print_report+0xd1/0x650 (?:?)
  srso_alias_return_thunk+0x5/0xfbef5 (?:?)
  __virt_addr_valid+0x1a7/0x340 (?:?)
  kasan_complete_mode_report_info+0x64/0x200 (?:?)
  kasan_report+0xf7/0x130 (?:?)
  snd_rawmidi_kernel_write1+0x9d/0x400 (?:?)
  __asan_load8+0x82/0xb0 (?:?)
  update_stack_state+0x1ef/0x2d0 (?:?)
  snd_rawmidi_kernel_write+0x1a/0x20 (?:?)
  seq_ump_process_event+0xd4/0x120 (sound/core/seq/seq_ump_client.c:82)
  __snd_seq_deliver_single_event+0x8a/0xe0 (?:?)
  snd_seq_deliver_from_ump+0x2b2/0xd60 (?:?)
  lock_acquire+0x14e/0x2e0 (?:?)
  find_held_lock+0x31/0x90 (?:?)
  snd_seq_port_use_ptr+0xa6/0xe0 (?:?)
  __kasan_check_write+0x18/0x20 (?:?)
  do_raw_read_unlock+0x32/0xa0 (?:?)
  _raw_read_unlock+0x26/0x50 (?:?)
  snd_seq_deliver_single_event+0x45c/0x4b0 (?:?)
  snd_seq_deliver_event+0x10d/0x1b0 (?:?)
  snd_seq_client_enqueue_event+0x192/0x240 (?:?)
  snd_seq_write+0x2cd/0x450 (?:?)
  apparmor_file_permission+0x20/0x30 (?:?)
  security_file_permission+0x51/0x60 (?:?)
  vfs_write+0x1ce/0x850 (?:?)
  __fget_files+0x12b/0x220 (?:?)
  lock_release+0xc8/0x2a0 (?:?)
  __rcu_read_unlock+0x74/0x2d0 (?:?)
  __fget_files+0x135/0x220 (?:?)
  ksys_write+0x15a/0x180 (?:?)
  rcu_is_watching+0x24/0x60 (?:?)
  __x64_sys_write+0x46/0x60 (?:?)
  x64_sys_call+0x7d/0x20d0 (?:?)
  do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87)
  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)

Fixes: 81fd444aa371 ("ALSA: seq: Bind UMP device")
Signed-off-by: Zhang Cen <rollkingzzc@gmail.com>
Link: https://patch.msgid.link/20260520103249.3048345-1-rollkingzzc@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>