diff options
| author | Clement Lecigne <clecigne@google.com> | 2023-01-13 13:07:45 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-14 10:16:52 +0100 |
| commit | df02234e6b87d2a9a82acd3198e44bdeff8488c6 (patch) | |
| tree | d4990216b5b8a354a40817e776d71360561a847d /sound | |
| parent | f8ed0a93b5d576bbaf01639ad816473bdfd1dcb0 (diff) | |
ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF
[ Note: this is a fix that works around the bug equivalently as the
two upstream commits:
1fa4445f9adf ("ALSA: control - introduce snd_ctl_notify_one() helper")
56b88b50565c ("ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF")
but in a simpler way to fit with older stable trees -- tiwai ]
Add missing locking in ctl_elem_read_user/ctl_elem_write_user which can be
easily triggered and turned into an use-after-free.
Example code paths with SNDRV_CTL_IOCTL_ELEM_READ:
64-bits:
snd_ctl_ioctl
snd_ctl_elem_read_user
[takes controls_rwsem]
snd_ctl_elem_read [lock properly held, all good]
[drops controls_rwsem]
32-bits (compat):
snd_ctl_ioctl_compat
snd_ctl_elem_write_read_compat
ctl_elem_write_read
snd_ctl_elem_read [missing lock, not good]
CVE-2023-0266 was assigned for this issue.
Signed-off-by: Clement Lecigne <clecigne@google.com>
Cc: stable@kernel.org # 5.12 and older
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/core/control_compat.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c index 97467f6a32a1..980ab3580f1b 100644 --- a/sound/core/control_compat.c +++ b/sound/core/control_compat.c @@ -304,7 +304,9 @@ static int ctl_elem_read_user(struct snd_card *card, err = snd_power_wait(card, SNDRV_CTL_POWER_D0); if (err < 0) goto error; + down_read(&card->controls_rwsem); err = snd_ctl_elem_read(card, data); + up_read(&card->controls_rwsem); if (err < 0) goto error; err = copy_ctl_value_to_user(userdata, valuep, data, type, count); @@ -332,7 +334,9 @@ static int ctl_elem_write_user(struct snd_ctl_file *file, err = snd_power_wait(card, SNDRV_CTL_POWER_D0); if (err < 0) goto error; + down_write(&card->controls_rwsem); err = snd_ctl_elem_write(card, file, data); + up_write(&card->controls_rwsem); if (err < 0) goto error; err = copy_ctl_value_to_user(userdata, valuep, data, type, count); |