This is a note to let you know that I've just added the patch titled
ALSA: sb: Fix potential double-free of CSP mixer elements
to the 5.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
alsa-sb-fix-potential-double-free-of-csp-mixer-eleme.patch
and it can be found in the queue-5.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8442be789a958e2ff9302af8561645deb4975bc1
Author: Takashi Iwai <tiwai@xxxxxxx>
Date: Tue Jun 8 16:04:37 2021 +0200
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@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/sound/isa/sb/sb16_csp.c b/sound/isa/sb/sb16_csp.c
index 4789345a8fdd..c98ccd421a2e 100644
--- a/sound/isa/sb/sb16_csp.c
+++ b/sound/isa/sb/sb16_csp.c
@@ -1072,10 +1072,14 @@ 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 */
