[PATCH][next] ALSA: vmaster: Use flex_array_size() helper in memcpy()

["Gustavo A. R. Silva" <gustavoars@kernel.org>]

Make use of the flex_array_size() helper to calculate the size of a
flexible array member within an enclosing structure.

This helper offers defense-in-depth against potential integer overflows
and makes it explicitly clear that we are dealing with a flexible array
member.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 sound/core/vmaster.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
index ab36f9898711..21ce4082cb5f 100644
--- a/sound/core/vmaster.c
+++ b/sound/core/vmaster.c
@@ -262,7 +262,8 @@ int _snd_ctl_add_follower(struct snd_kcontrol *master,
 		return -ENOMEM;
 	srec->kctl = follower;
 	srec->follower = *follower;
-	memcpy(srec->follower.vd, follower->vd, follower->count * sizeof(*follower->vd));
+	memcpy(srec->follower.vd, follower->vd, flex_array_size(srec, follower.vd,
+								srec->follower.count));
 	srec->master = master_link;
 	srec->flags = flags;
 
-- 
2.27.0