diff options
author | Clement Lecigne <clecigne@google.com> | 2023-01-13 15:07:45 +0300 |
---|---|---|
committer | Takashi Iwai <tiwai@suse.de> | 2023-01-13 16:15:26 +0300 |
commit | 56b88b50565cd8b946a2d00b0c83927b7ebb055e (patch) | |
tree | 43fee411773c5e23bea239684a8bca805db8c574 /sound | |
parent | 92a9c0ad86d47ff4cce899012e355c400f02cfb8 (diff) | |
download | linux-56b88b50565cd8b946a2d00b0c83927b7ebb055e.tar.xz |
ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF
Takes rwsem lock inside snd_ctl_elem_read instead of snd_ctl_elem_read_user
like it was done for write in commit 1fa4445f9adf1 ("ALSA: control - introduce
snd_ctl_notify_one() helper"). Doing this way we are also fixing the following
locking issue happening in the compat path which can be easily triggered and
turned into an use-after-free.
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:
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.
Cc: stable@kernel.org # 5.13+
Signed-off-by: Clement Lecigne <clecigne@google.com>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230113120745.25464-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
-rw-r--r-- | sound/core/control.c | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/sound/core/control.c b/sound/core/control.c index 50e7ba66f187..82aa1af1d1d8 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -1203,14 +1203,19 @@ static int snd_ctl_elem_read(struct snd_card *card, const u32 pattern = 0xdeadbeef; int ret; + down_read(&card->controls_rwsem); kctl = snd_ctl_find_id(card, &control->id); - if (kctl == NULL) - return -ENOENT; + if (kctl == NULL) { + ret = -ENOENT; + goto unlock; + } index_offset = snd_ctl_get_ioff(kctl, &control->id); vd = &kctl->vd[index_offset]; - if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_READ) || kctl->get == NULL) - return -EPERM; + if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_READ) || kctl->get == NULL) { + ret = -EPERM; + goto unlock; + } snd_ctl_build_ioff(&control->id, kctl, index_offset); @@ -1220,7 +1225,7 @@ static int snd_ctl_elem_read(struct snd_card *card, info.id = control->id; ret = __snd_ctl_elem_info(card, kctl, &info, NULL); if (ret < 0) - return ret; + goto unlock; #endif if (!snd_ctl_skip_validation(&info)) @@ -1230,7 +1235,7 @@ static int snd_ctl_elem_read(struct snd_card *card, ret = kctl->get(kctl, control); snd_power_unref(card); if (ret < 0) - return ret; + goto unlock; if (!snd_ctl_skip_validation(&info) && sanity_check_elem_value(card, control, &info, pattern) < 0) { dev_err(card->dev, @@ -1238,8 +1243,11 @@ static int snd_ctl_elem_read(struct snd_card *card, control->id.iface, control->id.device, control->id.subdevice, control->id.name, control->id.index); - return -EINVAL; + ret = -EINVAL; + goto unlock; } +unlock: + up_read(&card->controls_rwsem); return ret; } @@ -1253,9 +1261,7 @@ static int snd_ctl_elem_read_user(struct snd_card *card, if (IS_ERR(control)) return PTR_ERR(control); - down_read(&card->controls_rwsem); result = snd_ctl_elem_read(card, control); - up_read(&card->controls_rwsem); if (result < 0) goto error; |