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Commit 9ec61849 authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman
Browse files

ALSA: sb: Fix potential double-free of CSP mixer elements 

[ Upstream commit c305366a37441c2ac90b08711cb6f032b43672f2 ]

snd_sb_qsound_destroy() contains the calls of removing the previously
created mixer controls, but it doesn't clear the pointers.  As
snd_sb_qsound_destroy() itself may be repeatedly called via ioctl,
this could lead to double-free potentially.

Fix it by clearing the struct fields properly afterwards.

Link: https://lore.kernel.org/r/20210608140540.17885-4-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent e4bb007a

sound/isa/sb/sb16_csp.c

+6 −2
Original line number Diff line number Diff line
@@ -1086,10 +1086,14 @@ static void snd_sb_qsound_destroy(struct snd_sb_csp * p) 
	card = p->chip->card;	

	

	down_write(&card->controls_rwsem);

	if (p->qsound_switch)

	if (p->qsound_switch) {

		snd_ctl_remove(card, p->qsound_switch);

	if (p->qsound_space)

		p->qsound_switch = NULL;

	}

	if (p->qsound_space) {

		snd_ctl_remove(card, p->qsound_space);

		p->qsound_space = NULL;

	}

	up_write(&card->controls_rwsem);



	/* cancel pending transfer of QSound parameters */