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authorAlan Young <consult.awy@gmail.com>2021-12-02 18:06:07 +0300
committerTakashi Iwai <tiwai@suse.de>2021-12-02 18:41:07 +0300
commitb6409dd6bdc03aa178bbff0d80db2a30d29b63ac (patch)
tree458214bfc473a5a363b860ee3c4a7c802447fbbe /sound
parent6665bb30a6b1a4a853d52557c05482ee50e71391 (diff)
downloadlinux-b6409dd6bdc03aa178bbff0d80db2a30d29b63ac.tar.xz
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.c3
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;
}