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

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: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2021-06-08 16:04:37 +02:00
parent 36e7b12b21
commit c305366a37
1 changed files with 6 additions and 2 deletions
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8
sound/isa/sb/sb16_csp.c
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@ -1077,10 +1077,14 @@ 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 */