From 1bbc033983b76f41d51d4a48838bf94c5e6b6f50 Mon Sep 17 00:00:00 2001 From: Danish Khateeb Date: Mon, 28 Sep 2026 13:23:52 -0500 Subject: [PATCH] ALSA: timer: Handle userspace-driven timer ioctls from 32-bit tasks 32-bit tasks on a 64-bit kernel can't use userspace-driven timers. The compat handler for /dev/snd/timer doesn't list SNDRV_TIMER_IOCTL_CREATE, so creating a timer fails with -ENOTTY. The file returned for a timer has no .compat_ioctl either, so SNDRV_TIMER_IOCTL_TRIGGER fails with -ENOTTY too. struct snd_timer_uinfo has the same layout for 32-bit and 64-bit tasks, and SNDRV_TIMER_IOCTL_TRIGGER takes no argument, so both commands can be passed through unchanged. The utimer selftest doesn't catch this when built with -m32: it takes -ENOTTY from SNDRV_TIMER_IOCTL_CREATE to mean CONFIG_SND_UTIMER=n and skips. Fixes: 37745918e0e7 ("ALSA: timer: Introduce virtual userspace-driven timers") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Danish Khateeb Link: https://patch.msgid.link/20260928182352.309457-1-danishkhateeb03@gmail.com Signed-off-by: Takashi Iwai --- sound/core/timer.c | 1 + sound/core/timer_compat.c | 1 + 2 files changed, 2 insertions(+) diff --git a/sound/core/timer.c b/sound/core/timer.c index 679b26435670..69a59b25fe0a 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -2176,6 +2176,7 @@ static const struct file_operations snd_utimer_fops = { .llseek = noop_llseek, .release = snd_utimer_release, .unlocked_ioctl = snd_utimer_ioctl, + .compat_ioctl = snd_utimer_ioctl, }; static int snd_utimer_start(struct snd_timer *t) diff --git a/sound/core/timer_compat.c b/sound/core/timer_compat.c index 25ee81c1668b..5bab00466de7 100644 --- a/sound/core/timer_compat.c +++ b/sound/core/timer_compat.c @@ -99,6 +99,7 @@ static long __snd_timer_user_ioctl_compat(struct file *file, unsigned int cmd, case SNDRV_TIMER_IOCTL_PAUSE: case SNDRV_TIMER_IOCTL_PAUSE_OLD: case SNDRV_TIMER_IOCTL_NEXT_DEVICE: + case SNDRV_TIMER_IOCTL_CREATE: return __snd_timer_user_ioctl(file, cmd, (unsigned long)argp, true); case SNDRV_TIMER_IOCTL_GPARAMS32: return snd_timer_user_gparams_compat(file, argp);