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| author | Alan Young <consult.awy@gmail.com> | 2021-12-02 15:06:07 +0000 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2021-12-02 16:41:07 +0100 |
| commit | b6409dd6bdc03aa178bbff0d80db2a30d29b63ac (patch) | |
| tree | 458214bfc473a5a363b860ee3c4a7c802447fbbe /sound | |
| parent | 6665bb30a6b1a4a853d52557c05482ee50e71391 (diff) | |
| download | linux-b6409dd6bdc03aa178bbff0d80db2a30d29b63ac.tar.bz2 | |
ALSA: ctl: Fix copy of updated id with element read/write
When control_compat.c:copy_ctl_value_to_user() is used, by
ctl_elem_read_user() & ctl_elem_write_user(), it must also copy back the
snd_ctl_elem_id value that may have been updated (filled in) by the call
to snd_ctl_elem_read/snd_ctl_elem_write().
This matches the functionality provided by snd_ctl_elem_read_user() and
snd_ctl_elem_write_user(), via snd_ctl_build_ioff().
Without this, and without making additional calls to snd_ctl_info()
which are unnecessary when using the non-compat calls, a userspace
application will not know the numid value for the element and
consequently will not be able to use the poll/read interface on the
control file to determine which elements have updates.
Signed-off-by: Alan Young <consult.awy@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211202150607.543389-1-consult.awy@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/core/control_compat.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c index 470dabc60aa0..edff063e088d 100644 --- a/sound/core/control_compat.c +++ b/sound/core/control_compat.c @@ -264,6 +264,7 @@ static int copy_ctl_value_to_user(void __user *userdata, struct snd_ctl_elem_value *data, int type, int count) { + struct snd_ctl_elem_value32 __user *data32 = userdata; int i, size; if (type == SNDRV_CTL_ELEM_TYPE_BOOLEAN || @@ -280,6 +281,8 @@ static int copy_ctl_value_to_user(void __user *userdata, if (copy_to_user(valuep, data->value.bytes.data, size)) return -EFAULT; } + if (copy_to_user(&data32->id, &data->id, sizeof(data32->id))) + return -EFAULT; return 0; } |