kernel/linux.git/sound/core, branch v6.18.36

ALSA: timer: Fix UAF at snd_timer_user_params()

2026-06-19T11:44:04+00:00

commit 053a401b592be424fea9d57c789f66cd5d8cec11 upstream. At releasing a timer object, e.g. when a userspace timer (CONFIG_SND_UTIMER) gets closed and snd_timer_free() is called, it tries to detach the timer instances and release the resources. However, it's still possible that other in-flight tasks are holding the timer instance where the to-be-deleted timer object is associated, and this may lead to racy accesses. Fortunately, most of ioctls dealing with the timer instance list already have the protection with register_mutex, and this also avoids such races. But, SNDRV_TIMER_IOCTL_PARAMS isn't protected, hence the concurrent ioctl may lead to use-after-free. This patch just adds the guard with register_mutex to protect snd_timer_user_params() for covering the code path as a quick workaround. It's no hot-path but rather a rarely issued ioctl, so the performance penalty doesn't matter. Reported-by: Kyle Zeng Tested-by: Kyle Zeng Cc: Link: https://patch.msgid.link/20260606161145.1933447-2-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: timer: Forcibly close timer instances at closing

2026-06-19T11:44:04+00:00

commit da3039e91d1f835874ed6e9a33ea19ee80c2cb92 upstream. When snd_timer object is freed via snd_timer_free() and still pending snd_timer_instance objects are assigned to the timer object, it tries to unlink all instances and just set NULL to each ti->timer, then releases the resources immediately. The problem is, however, when there are slave timer instances that are associated with a master instance linked to this timer: namely, those slave instances still point to the freed timer object although the master instance is unlinked, which may lead to user-after-free. The bug can be easily triggered particularly when a new userspace-driven timers (CONFIG_SND_UTIMER) is involved, since it can create and delete the timer object via a simple file open/close, while the other applications may keep accessing to that timer. This patch is an attempt to paper over the problem above: now instead of just unlinking, call snd_timer_close[_locked]() forcibly for each pending timer instance, so that all assigned slave timer instances are properly detached, too. Since snd_timer_close() might be called later by the driver that created that instance, the check of SNDRV_TIMER_IFLG_DEAD is added at the beginning, too. Reported-by: Kyle Zeng Tested-by: Kyle Zeng Fixes: 37745918e0e7 ("ALSA: timer: Introduce virtual userspace-driven timers") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260606161145.1933447-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: seq: dummy: fix UMP event stack overread

2026-06-19T11:43:56+00:00

[ 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 Link: https://patch.msgid.link/20260605080204.32045-1-kylebot@openai.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: PCM: Fix wait queue list corruption in snd_pcm_drain() on linked streams

2026-06-19T11:43:56+00:00

[ Upstream commit 88fe2e3658726cb21ff2dcf9770bf672f9b9d31b ] snd_pcm_drain() uses init_waitqueue_entry which does not clear entry.prev/next, and add_wait_queue with a conditional remove_wait_queue that is skipped when to_check is no longer in the group after concurrent UNLINK. The orphaned wait entry remains on the unlinked substream sleep queue. On the next drain iteration, add_wait_queue adds the entry to a new queue while still linked on the old one, corrupting both lists. A subsequent wake_up dereferences NULL at the func pointer (mapped from the spinlock at offset 0 of the misinterpreted wait_queue_head_t), causing a kernel panic. Replace init_waitqueue_entry/add_wait_queue/conditional remove_wait_queue with init_wait_entry/prepare_to_wait/ finish_wait. init_wait_entry clears prev/next via INIT_LIST_HEAD on each iteration and sets autoremove_wake_function which auto-removes the entry on wake-up. finish_wait safely handles both the already-removed and still-queued cases. Fixes: 9b1dbd69ba6f ("ALSA: pcm: fix use-after-free on linked stream runtime in snd_pcm_drain") Signed-off-by: Ji'an Zhou Link: https://patch.msgid.link/20260604142559.3840881-1-eilaimemedsnaimel@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: pcm: oss: Fix setup list UAF on proc write error

2026-06-09T10:28:25+00:00

[ Upstream commit 4cc54bdd54b337e77115be5b55577d1c58608eae ] snd_pcm_oss_proc_write() links a newly allocated setup entry into the OSS setup list before duplicating the task name. If the task-name allocation fails, the error path frees the already linked entry and leaves setup_list pointing at freed memory. A later OSS device open can then walk the stale list entry in snd_pcm_oss_look_for_setup() and dereference freed memory. Allocate the task name and initialize the setup entry before publishing the entry on setup_list. Also fetch the initial proc read iterator only after taking setup_mutex, so all setup_list traversal follows the same list lifetime rules. Reported-by: syzbot+8e498074a794999eb41c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6a1062b7.170a0220.35b2b7.0003.GAE@google.com Closes: https://syzkaller.appspot.com/bug?extid=8e498074a794999eb41c Fixes: 060d77b9c04a ("[ALSA] Fix / clean up PCM-OSS setup hooks") Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260522-alsa-pcm-oss-setup-uaf-v1-1-40bdcc4d17e8@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: seq: Serialize UMP output teardown with event_input

2026-06-01T15:51:05+00:00

[ 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 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 Link: https://patch.msgid.link/20260520103249.3048345-1-rollkingzzc@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: pcm: Don't setup bogus iov_iter for silencing

2026-06-01T15:50:40+00:00

commit e4d3386b74fba8e01280484b67ee481ece00201e upstream. At transition to the iov_iter for PCM data transfer, we blindly applied the iov_iter setup also for silencing (i.e. data = NULL), and it leads to a calculation of bogus iov_iter. Fortunately this didn't cause troubles on most of architectures but it goes wrong on RISC-V now, causing a NULL dereference. Handle the NULL data case to treat the silencing in interleaved_copy() for addressing the bug above. noninterleaved_copy() has already the NULL data handling, so it doesn't need changes. Reported-by: Jiakai Xu Closes: https://lore.kernel.org/20260515051516.3103036-1-xujiakai24@mails.ucas.ac.cn Fixes: cf393babb37a ("ALSA: pcm: Add copy ops with iov_iter") Cc: Link: https://patch.msgid.link/20260517165121.31399-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: core: Validate compress device numbers without dynamic minors

2026-05-23T11:06:38+00:00

[ Upstream commit 796e119e9b14763be905ad0d023c71a14bc2e931 ] Without CONFIG_SND_DYNAMIC_MINORS, ALSA reserves only two fixed minors for compress devices on each card: comprD0 and comprD1. snd_find_free_minor() currently computes the compress minor as type + dev without validating dev first, so device numbers greater than 1 spill into the HWDEP minor range instead of failing registration. ASoC passes rtd->id to snd_compress_new(), so this can happen on real non-dynamic-minor builds. Add a dedicated fixed-minor check for SNDRV_DEVICE_TYPE_COMPRESS in snd_find_free_minor() and reject out-of-range device numbers with -EINVAL before constructing the minor. Also remove the stale TODO in compress_offload.c that still claims multiple compress nodes are missing. Fixes: 3eafc959b32f ("ALSA: core: add support for compressed devices") Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260325-alsa-compress-static-minors-v1-1-0628573bee1c@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: seq: Fix UMP group 16 filtering

2026-05-14T13:30:13+00:00

commit 92429ca999db99febced82f23362a71b2ba4c1d8 upstream. The sequencer UAPI defines group_filter as an unsigned int bitmap. Bit 0 filters groupless messages and bits 1-16 filter UMP groups 1-16. The internal snd_seq_client storage is only unsigned short, so bit 16 is truncated when userspace sets the filter. The same truncation affects the automatic UMP client filter used to avoid delivery to inactive groups, so events for group 16 cannot be filtered. Store the internal bitmap as unsigned int and keep both userspace-provided and automatically generated values limited to the defined UAPI bits. Fixes: d2b706077792 ("ALSA: seq: Add UMP group filter") Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260506-alsa-seq-ump-group16-filter-v1-1-b75160bf6993@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: core: Serialize deferred fasync state checks

2026-05-14T13:30:13+00:00

commit 5337213381df578058e2e41da93cbd0e4639935f upstream. snd_fasync_helper() updates fasync->on under snd_fasync_lock, and snd_fasync_work_fn() now also evaluates fasync->on under the same lock. snd_kill_fasync() still tests the flag before taking the lock, leaving an unsynchronized read against FASYNC enable/disable updates. Move the enabled-state check into the locked section. Also clear fasync->on under snd_fasync_lock in snd_fasync_free() before unlinking the pending entry. Together with the locked sender-side check, this publishes teardown before flushing the deferred work and prevents a racing sender from requeueing the entry after free has started. Fixes: ef34a0ae7a26 ("ALSA: core: Add async signal helpers") Fixes: 8146cd333d23 ("ALSA: core: Fix potential data race at fasync handling") Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260506-alsa-core-fasync-on-lock-v1-1-ea48c77d6ca4@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman