This is a note to let you know that I've just added the patch titled
ALSA: sb: Fix two use after free in snd_sb_qsound_build
to the 4.4-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-two-use-after-free-in-snd_sb_qsound_build.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4fb44dd2c1dda18606348acdfdb97e8759dde9df Mon Sep 17 00:00:00 2001
From: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>
Date: Mon, 26 Apr 2021 07:55:41 -0700
Subject: ALSA: sb: Fix two use after free in snd_sb_qsound_build
From: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>
commit 4fb44dd2c1dda18606348acdfdb97e8759dde9df upstream.
In snd_sb_qsound_build, snd_ctl_add(..,p->qsound_switch...) and
snd_ctl_add(..,p->qsound_space..) are called. But the second
arguments of snd_ctl_add() could be freed via snd_ctl_add_replace()
->snd_ctl_free_one(). After the error code is returned,
snd_sb_qsound_destroy(p) is called in __error branch.
But in snd_sb_qsound_destroy(), the freed p->qsound_switch and
p->qsound_space are still used by snd_ctl_remove().
My patch set p->qsound_switch and p->qsound_space to NULL if
snd_ctl_add() failed to avoid the uaf bugs. But these codes need
to further be improved with the code style.
Signed-off-by: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210426145541.8070-1-lyl2019@xxxxxxxxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/isa/sb/sb16_csp.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/sound/isa/sb/sb16_csp.c
+++ b/sound/isa/sb/sb16_csp.c
@@ -1059,10 +1059,14 @@ static int snd_sb_qsound_build(struct sn
spin_lock_init(&p->q_lock);
- if ((err = snd_ctl_add(card, p->qsound_switch = snd_ctl_new1(&snd_sb_qsound_switch, p))) < 0)
+ if ((err = snd_ctl_add(card, p->qsound_switch = snd_ctl_new1(&snd_sb_qsound_switch, p))) < 0) {
+ p->qsound_switch = NULL;
goto __error;
- if ((err = snd_ctl_add(card, p->qsound_space = snd_ctl_new1(&snd_sb_qsound_space, p))) < 0)
+ }
+ if ((err = snd_ctl_add(card, p->qsound_space = snd_ctl_new1(&snd_sb_qsound_space, p))) < 0) {
+ p->qsound_space = NULL;
goto __error;
+ }
return 0;
Patches currently in stable-queue which might be from lyl2019@xxxxxxxxxxxxxxxx are
queue-4.4/alsa-emu8000-fix-a-use-after-free-in-snd_emu8000_create_mixer.patch
queue-4.4/alsa-sb-fix-two-use-after-free-in-snd_sb_qsound_build.patch
