[v4 PATCH] ALSA: virtio: Fix "Coverity: virtsnd_kctl_tlv_op(): Uninitialized variables" warning.

Aiswarya Cyriac
2024-02-16T10:07:48Z

This commit fixes the following warning when building virtio_snd driver.

"
*** CID 1583619: Uninitialized variables (UNINIT)
sound/virtio/virtio_kctl.c:294 in virtsnd_kctl_tlv_op()
288
289 break;
290 }
291
292 kfree(tlv);
293
vvv CID 1583619: Uninitialized variables (UNINIT)
vvv Using uninitialized value "rc".
294 return rc;
295 }
296
297 /**
298 * virtsnd_kctl_get_enum_items() - Query items for the ENUMERATED element type.
299 * @snd: VirtIO sound device.
"

This warning is caused by the absence of the "default" branch in the
switch-block, and is a false positive because the kernel calls
virtsnd_kctl_tlv_op() only with values for op_flag processed in
this block.

Also, this commit unifies the cleanup path for all possible control
paths in the callback function.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
Signed-off-by: Aiswarya Cyriac <aiswarya.cyriac@opensynergy.com>
Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1583619 ("Uninitialized variables")
Fixes: d6568e3de42d ("ALSA: virtio: add support for audio controls")
---
sound/virtio/virtio_kctl.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/sound/virtio/virtio_kctl.c b/sound/virtio/virtio_kctl.c
index 0c6ac74aca1e..7aa79c05b464 100644
--- a/sound/virtio/virtio_kctl.c
+++ b/sound/virtio/virtio_kctl.c
@@ -253,8 +253,8 @@ static int virtsnd_kctl_tlv_op(struct snd_kcontrol *kcontrol, int op_flag,

tlv = kzalloc(size, GFP_KERNEL);
if (!tlv) {
- virtsnd_ctl_msg_unref(msg);
- return -ENOMEM;
+ rc = -ENOMEM;
+ goto on_msg_unref;
}

sg_init_one(&sg, tlv, size);
@@ -281,14 +281,25 @@ static int virtsnd_kctl_tlv_op(struct snd_kcontrol *kcontrol, int op_flag,
hdr->hdr.code =
cpu_to_le32(VIRTIO_SND_R_CTL_TLV_COMMAND);

- if (copy_from_user(tlv, utlv, size))
+ if (copy_from_user(tlv, utlv, size)) {
rc = -EFAULT;
- else
+ goto on_msg_unref;
+ } else {
rc = virtsnd_ctl_msg_send(snd, msg, &sg, NULL, false);
+ }

break;
+ default:
+ rc = -EINVAL;
+ /* We never get here - we listed all values for op_flag */
+ WARN_ON(1);
+ goto on_msg_unref;
}
+ kfree(tlv);
+ return rc;

+on_msg_unref:
+ virtsnd_ctl_msg_unref(msg);
kfree(tlv);

return rc;
--
2.43.2