kernel/linux.git/sound/core, branch v6.1.176

ALSA: timer: Fix UAF at snd_timer_user_params()

2026-06-19T11:37:14+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: PCM: Fix wait queue list corruption in snd_pcm_drain() on linked streams

2026-06-19T11:37:10+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: core: Serialize deferred fasync state checks

2026-06-01T15:39:31+00:00

[ Upstream commit 5337213381df578058e2e41da93cbd0e4639935f ] 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: Sasha Levin

ALSA: misc: Use guard() for spin locks

2026-06-01T15:39:31+00:00

[ Upstream commit b8e1684163ae52db90f428965bd9aaff7205c02e ] Clean up the code using guard() for spin locks. Merely code refactoring, and no behavior change. Signed-off-by: Takashi Iwai Link: https://patch.msgid.link/20250829151335.7342-20-tiwai@suse.de Stable-dep-of: 5337213381df ("ALSA: core: Serialize deferred fasync state checks") Signed-off-by: Sasha Levin

ALSA: core: Validate compress device numbers without dynamic minors

2026-06-01T15:39:10+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: core: Fix potential data race at fasync handling

2026-06-01T15:38:47+00:00

commit 8146cd333d235ed32d48bb803fdf743472d7c783 upstream. In snd_fasync_work_fn(), which is the offload work for traversing and processing the pending fasync list, the call of kill_fasync() is done outside the snd_fasync_lock for avoiding deadlocks. The problem is that its the references of fasync->on, fasync->signal and fasync->poll are done there also outside the lock. Since these may be modified by snd_kill_fasync() call concurrently from other process, inconsistent values might be passed to kill_fasync(). Although there shouldn't be critical UAF, it's still better to be addressed. This patch moves the kill_fasync() argument evaluations inside the snd_fasync_lock for avoiding the data races above. The handling in fasync->on flag is optimized in the loop to skip directly. Also, for more clarity, snd_fasync_free() takes the lock and unlink the pending entry more directly instead of clearing fasync->on flag. Reported-by: Jake Lamberson Fixes: ef34a0ae7a26 ("ALSA: core: Add async signal helpers") Cc: Link: https://patch.msgid.link/20260420061721.3253644-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

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: control: Validate buf_len before strnlen() in snd_ctl_elem_init_enum_names()

2026-06-01T15:38:45+00:00

commit e0da8a8cac74f4b9f577979d131f0d2b88a84487 upstream. snd_ctl_elem_init_enum_names() advances pointer p through the names buffer while decrementing buf_len. If buf_len reaches zero but items remain, the next iteration calls strnlen(p, 0). While strnlen(p, 0) returns 0 and would hit the existing name_len == 0 error path, CONFIG_FORTIFY_SOURCE's fortified strnlen() first checks maxlen against __builtin_dynamic_object_size(). When Clang loses track of p's object size inside the loop, this triggers a BRK exception panic before the return value is examined. Add a buf_len == 0 guard at the loop entry to prevent calling fortified strnlen() on an exhausted buffer. Found by kernel fuzz testing through Xiaomi Smartphone. Fixes: 8d448162bda5 ("ALSA: control: add support for ENUMERATED user space controls") Cc: stable@vger.kernel.org Signed-off-by: Ziqing Chen Link: https://patch.msgid.link/20260414132437.261304-1-chenziqing@xiaomi.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: control: Avoid WARN() for symlink errors

2026-06-01T15:38:41+00:00

commit b2e538a9827dd04ab5273bf4be8eb2edb84357b0 upstream. Using WARN() for showing the error of symlink creations don't give more information than telling that something goes wrong, since the usual code path is a lregister callback from each control element creation. More badly, the use of WARN() rather confuses fuzzer as if it were serious issues. This patch downgrades the warning messages to use the normal dev_err() instead of WARN(). For making it clearer, add the function name to the prefix, too. Fixes: a135dfb5de15 ("ALSA: led control - add sysfs kcontrol LED marking layer") Reported-by: syzbot+4e7919b09c67ffd198ae@syzkaller.appspotmail.com Closes: https://lore.kernel.org/675664c7.050a0220.a30f1.018c.GAE@google.com Link: https://patch.msgid.link/20241209095614.4273-1-tiwai@suse.de Signed-off-by: Takashi Iwai [ Use card->ctl_dev.kobj to keep struct consistent. ] Signed-off-by: Robert Garcia Signed-off-by: Greg Kroah-Hartman

ALSA: pcm: fix use-after-free on linked stream runtime in snd_pcm_drain()

2026-03-25T10:03:15+00:00

[ Upstream commit 9b1dbd69ba6f8f8c69bc7b77c2ce3b9c6ed05ba6 ] In the drain loop, the local variable 'runtime' is reassigned to a linked stream's runtime (runtime = s->runtime at line 2157). After releasing the stream lock at line 2169, the code accesses runtime->no_period_wakeup, runtime->rate, and runtime->buffer_size (lines 2170-2178) — all referencing the linked stream's runtime without any lock or refcount protecting its lifetime. A concurrent close() on the linked stream's fd triggers snd_pcm_release_substream() → snd_pcm_drop() → pcm_release_private() → snd_pcm_unlink() → snd_pcm_detach_substream() → kfree(runtime). No synchronization prevents kfree(runtime) from completing while the drain path dereferences the stale pointer. Fix by caching the needed runtime fields (no_period_wakeup, rate, buffer_size) into local variables while still holding the stream lock, and using the cached values after the lock is released. Fixes: f2b3614cefb6 ("ALSA: PCM - Don't check DMA time-out too shortly") Cc: stable@vger.kernel.org Signed-off-by: Mehul Rao Link: https://patch.msgid.link/20260305193508.311096-1-mehulrao@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman