This is a note to let you know that I've just added the patch titled
ALSA: emu8000: Fix a use after free in snd_emu8000_create_mixer
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-emu8000-fix-a-use-after-free-in-snd_emu8000_create_mixer.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 1c98f574403dbcf2eb832d5535a10d967333ef2d Mon Sep 17 00:00:00 2001
From: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>
Date: Mon, 26 Apr 2021 06:11:29 -0700
Subject: ALSA: emu8000: Fix a use after free in snd_emu8000_create_mixer
From: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>
commit 1c98f574403dbcf2eb832d5535a10d967333ef2d upstream.
Our code analyzer reported a uaf.
In snd_emu8000_create_mixer, the callee snd_ctl_add(..,emu->controls[i])
calls snd_ctl_add_replace(.., kcontrol,..). Inside snd_ctl_add_replace(),
if error happens, kcontrol will be freed by snd_ctl_free_one(kcontrol).
Then emu->controls[i] points to a freed memory, and the execution comes
to __error branch of snd_emu8000_create_mixer. The freed emu->controls[i]
is used in snd_ctl_remove(card, emu->controls[i]).
My patch set emu->controls[i] to NULL if snd_ctl_add() failed to avoid
the uaf.
Signed-off-by: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210426131129.4796-1-lyl2019@xxxxxxxxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/isa/sb/emu8000.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/sound/isa/sb/emu8000.c
+++ b/sound/isa/sb/emu8000.c
@@ -1042,8 +1042,10 @@ snd_emu8000_create_mixer(struct snd_card
memset(emu->controls, 0, sizeof(emu->controls));
for (i = 0; i < EMU8000_NUM_CONTROLS; i++) {
- if ((err = snd_ctl_add(card, emu->controls[i] = snd_ctl_new1(mixer_defs[i], emu))) < 0)
+ if ((err = snd_ctl_add(card, emu->controls[i] = snd_ctl_new1(mixer_defs[i], emu))) < 0) {
+ emu->controls[i] = 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
