From e6645e625480cdf1079a4265f758d13b70721029 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 9 Feb 2026 13:12:11 +0100 Subject: [PATCH] ALSA: mixer: oss: Add card disconnect checkpoints [ Upstream commit 084d5d44418148662365eced3e126ad1a81ee3e2 ] ALSA OSS mixer layer calls the kcontrol ops rather individually, and pending calls might be not always caught at disconnecting the device. For avoiding the potential UAF scenarios, add sanity checks of the card disconnection at each entry point of OSS mixer accesses. The rwsem is taken just before that check, hence the rest context should be covered by that properly. Link: https://patch.msgid.link/20260209121212.171430-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/core/oss/mixer_oss.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c index e839a4bb93f8..aa98caaaea3c 100644 --- a/sound/core/oss/mixer_oss.c +++ b/sound/core/oss/mixer_oss.c @@ -525,6 +525,8 @@ static void snd_mixer_oss_get_volume1_vol(struct snd_mixer_oss_file *fmixer, if (numid == ID_UNKNOWN) return; guard(rwsem_read)(&card->controls_rwsem); + if (card->shutdown) + return; kctl = snd_ctl_find_numid(card, numid); if (!kctl) return; @@ -558,6 +560,8 @@ static void snd_mixer_oss_get_volume1_sw(struct snd_mixer_oss_file *fmixer, if (numid == ID_UNKNOWN) return; guard(rwsem_read)(&card->controls_rwsem); + if (card->shutdown) + return; kctl = snd_ctl_find_numid(card, numid); if (!kctl) return; @@ -618,6 +622,8 @@ static void snd_mixer_oss_put_volume1_vol(struct snd_mixer_oss_file *fmixer, if (numid == ID_UNKNOWN) return; guard(rwsem_read)(&card->controls_rwsem); + if (card->shutdown) + return; kctl = snd_ctl_find_numid(card, numid); if (!kctl) return; @@ -655,6 +661,8 @@ static void snd_mixer_oss_put_volume1_sw(struct snd_mixer_oss_file *fmixer, if (numid == ID_UNKNOWN) return; guard(rwsem_read)(&card->controls_rwsem); + if (card->shutdown) + return; kctl = snd_ctl_find_numid(card, numid); if (!kctl) return; @@ -792,6 +800,8 @@ static int snd_mixer_oss_get_recsrc2(struct snd_mixer_oss_file *fmixer, unsigned if (uinfo == NULL || uctl == NULL) return -ENOMEM; guard(rwsem_read)(&card->controls_rwsem); + if (card->shutdown) + return -ENODEV; kctl = snd_mixer_oss_test_id(mixer, "Capture Source", 0); if (!kctl) return -ENOENT; @@ -835,6 +845,8 @@ static int snd_mixer_oss_put_recsrc2(struct snd_mixer_oss_file *fmixer, unsigned if (uinfo == NULL || uctl == NULL) return -ENOMEM; guard(rwsem_read)(&card->controls_rwsem); + if (card->shutdown) + return -ENODEV; kctl = snd_mixer_oss_test_id(mixer, "Capture Source", 0); if (!kctl) return -ENOENT; @@ -878,6 +890,8 @@ static int snd_mixer_oss_build_test(struct snd_mixer_oss *mixer, struct slot *sl int err; scoped_guard(rwsem_read, &card->controls_rwsem) { + if (card->shutdown) + return -ENODEV; kcontrol = snd_mixer_oss_test_id(mixer, name, index); if (kcontrol == NULL) return 0; @@ -1002,6 +1016,8 @@ static int snd_mixer_oss_build_input(struct snd_mixer_oss *mixer, if (snd_mixer_oss_build_test_all(mixer, ptr, &slot)) return 0; guard(rwsem_read)(&mixer->card->controls_rwsem); + if (mixer->card->shutdown) + return -ENODEV; kctl = NULL; if (!ptr->index) kctl = snd_mixer_oss_test_id(mixer, "Capture Source", 0);