linux-kernel - [PATCH 5.16 0446/1039] ALSA: PCM: Add missing rwsem around snd_ctl

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Date:   Mon, 24 Jan 2022 19:37:15 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Takashi Iwai <tiwai@...e.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0446/1039] ALSA: PCM: Add missing rwsem around snd_ctl_remove() calls

From: Takashi Iwai <tiwai@...e.de>

[ Upstream commit 5471e9762e1af4b7df057a96bfd46cc250979b88 ]

snd_ctl_remove() has to be called with card->controls_rwsem held (when
called after the card instantiation).  This patch add the missing
rwsem calls around it.

Fixes: a8ff48cb7083 ("ALSA: pcm: Free chmap at PCM free callback, too")
Link: https://lore.kernel.org/r/20211116071314.15065-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/core/pcm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 6fd3677685d70..ba4a987ed1c62 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -810,7 +810,11 @@ EXPORT_SYMBOL(snd_pcm_new_internal);
 static void free_chmap(struct snd_pcm_str *pstr)
 {
 	if (pstr->chmap_kctl) {
-		snd_ctl_remove(pstr->pcm->card, pstr->chmap_kctl);
+		struct snd_card *card = pstr->pcm->card;
+
+		down_write(&card->controls_rwsem);
+		snd_ctl_remove(card, pstr->chmap_kctl);
+		up_write(&card->controls_rwsem);
 		pstr->chmap_kctl = NULL;
 	}
 }
-- 
2.34.1