kernel/linux.git/sound/core/seq, branch v6.1.178

ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup()

2026-07-24T13:55:19+00:00

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 Link: https://patch.msgid.link/20260623233841.853326-1-sammiee5311@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Check UMP support for midi_version change

2026-07-24T13:55:19+00:00

commit 8765429279e7d3d68d39ace5f84af2815174bb1e upstream. When the kernel is built without UMP support but a user-space app requires the midi_version > 0, the kernel should return an error. Otherwise user-space assumes as if it were possible to deal, eventually hitting serious errors later. Fixes: 46397622a3fa ("ALSA: seq: Add UMP support") Cc: Link: https://patch.msgid.link/20241231145358.21946-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Skip event type filtering for UMP events

2026-07-24T13:55:19+00:00

commit 32108c22ac619c32dd6db594319e259b63bfb387 upstream. UMP events don't use the event type field, hence it's invalid to apply the filter, which may drop the events unexpectedly. Skip the event filtering for UMP events, instead. Fixes: 46397622a3fa ("ALSA: seq: Add UMP support") Cc: Link: https://patch.msgid.link/20240819084156.10286-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Avoid confusion of aligned read size

2026-07-24T13:55:18+00:00

commit 8c15a18331191b67bdce54d21af068baec044baf upstream. Currently the read event packet size in snd_seq_read() is defined by client->midi_version value that is guaranteed to be zero if UMP isn't enabled. But the static analyzer doesn't know of the fact, and it still suspects as if it were leading to a potential overflow. Add the more explicit check of CONFIG_SND_SEQ_UMP to determine the aligned_size value for avoiding the confusion. Fixes: 46397622a3fa ("ALSA: seq: Add UMP support") Reported-by: kernel test robot Reported-by: Dan Carpenter Closes: https://lore.kernel.org/r/202305261415.NY0vapZK-lkp@intel.com/ Link: https://lore.kernel.org/r/20230605144758.6677-2-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Clear variable event pointer on read

2026-07-24T13:54:39+00:00

[ 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 Link: https://patch.msgid.link/20260607004129.61345-1-kylebot@openai.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: seq: Add UMP support

2026-07-24T13:54:39+00:00

[ Upstream commit 46397622a3fa8372b8fda0f04b33d16923b03b1b ] Starting from this commit, we add the basic support of UMP (Universal MIDI Packet) events on ALSA sequencer infrastructure. The biggest change here is that, for transferring UMP packets that are up to 128 bits, we extend the data payload of ALSA sequencer event record when the client is declared to support for the new UMP events. A new event flag bit, SNDRV_SEQ_EVENT_UMP, is defined and it shall be set for the UMP packet events that have the larger payload of 128 bits, defined as struct snd_seq_ump_event. For controlling the UMP feature enablement in kernel, a new Kconfig, CONFIG_SND_SEQ_UMP is introduced. The extended event for UMP is available only when this Kconfig item is set. Similarly, the size of the internal snd_seq_event_cell also increases (in 4 bytes) when the Kconfig item is set. (But the size increase is effective only for 32bit architectures; 64bit archs already have padding there.) Overall, when CONFIG_SND_SEQ_UMP isn't set, there is no change in the event and cell, keeping the old sizes. For applications that want to access the UMP packets, first of all, a sequencer client has to declare the user-protocol to match with the latest one via the new SNDRV_SEQ_IOCTL_USER_PVERSION; otherwise it's treated as if a legacy client without UMP support. Then the client can switch to the new UMP mode (MIDI 1.0 or MIDI 2.0) with a new field, midi_version, in snd_seq_client_info. When switched to UMP mode (midi_version = 1 or 2), the client can write the UMP events with SNDRV_SEQ_EVENT_UMP flag. For reads, the alignment size is changed from snd_seq_event (28 bytes) to snd_seq_ump_event (32 bytes). When a UMP sequencer event is delivered to a legacy sequencer client, it's ignored or handled as an error. Conceptually, ALSA sequencer client and port correspond to the UMP Endpoint and Group, respectively; each client may have multiple ports and each port has the fixed number (16) of channels, total up to 256 channels. As of this commit, ALSA sequencer core just sends and receives the UMP events as-is from/to clients. The automatic conversions between the legacy events and the new UMP events will be implemented in a later patch. Along with this commit, bump the sequencer protocol version to 1.0.3. Reviewed-by: Jaroslav Kysela Link: https://lore.kernel.org/r/20230523075358.9672-26-tiwai@suse.de Signed-off-by: Takashi Iwai Stable-dep-of: 705dd6dcbc0e ("ALSA: seq: Clear variable event pointer on read") Signed-off-by: Sasha Levin

ALSA: seq: Introduce SNDRV_SEQ_IOCTL_USER_PVERSION ioctl

2026-07-24T13:54:39+00:00

[ Upstream commit afb72505e4614a2ccefe3440d37dec3a2273c330 ] For the future extension of ALSA sequencer ABI, introduce a new ioctl SNDRV_SEQ_IOCTL_USER_PVERSION. This is similar like the ioctls used in PCM and other interfaces, for an application to specify its supporting ABI version. The use of this ioctl will be mandatory for the upcoming UMP support. Reviewed-by: Jaroslav Kysela Link: https://lore.kernel.org/r/20230523075358.9672-25-tiwai@suse.de Signed-off-by: Takashi Iwai Stable-dep-of: 705dd6dcbc0e ("ALSA: seq: Clear variable event pointer on read") Signed-off-by: Sasha Levin

ALSA: seq: midi: Serialize output teardown with event_input

2026-07-24T13:54:36+00:00

[ 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 Link: https://patch.msgid.link/20260527062948.3614025-1-rollkingzzc@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: seq_oss: return full count for successful SEQ_FULLSIZE writes

2026-06-01T15:38:46+00:00

commit bbc6c0dda54fc0ad8f8aed0b796c23e186e1a188 upstream. snd_seq_oss_write() currently returns the raw load_patch() callback result for SEQ_FULLSIZE events. That callback is documented as returning 0 on success and -errno on failure, but snd_seq_oss_write() is the file write path and should report the number of user bytes consumed on success. Some in-tree backends also return backend-specific positive values, which can still be shorter than the original write size. Return the full byte count for successful SEQ_FULLSIZE writes. Preserve negative errors and convert any nonnegative completion to the original count. Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260324-alsa-seq-oss-fullsize-write-return-v1-1-66d448510538@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Improve data consistency at polling

2025-06-04T12:40:08+00:00

[ Upstream commit e3cd33ab17c33bd8f1a9df66ec83a15dd8f7afbb ] snd_seq_poll() calls snd_seq_write_pool_allocated() that reads out a field in client->pool object, while it can be updated concurrently via ioctls, as reported by syzbot. The data race itself is harmless, as it's merely a poll() call, and the state is volatile. OTOH, the read out of poll object info from the caller side is fragile, and we can leave it better in snd_seq_pool_poll_wait() alone. A similar pattern is seen in snd_seq_kernel_client_write_poll(), too, which is called from the OSS sequencer. This patch drops the pool checks from the caller side and add the pool->lock in snd_seq_pool_poll_wait() for better data consistency. Reported-by: syzbot+2d373c9936c00d7e120c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/67c88903.050a0220.15b4b9.0028.GAE@google.com Link: https://patch.msgid.link/20250307084246.29271-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin