linux-kernel - [PATCH] virtio_ring: fix uninitialized used value

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Message-ID: <20250725083635.73355-1-jasowang@redhat.com>
Date: Fri, 25 Jul 2025 16:36:35 +0800
From: Jason Wang <jasowang@...hat.com>
To: mst@...hat.com,
	jasowang@...hat.com
Cc: xuanzhuo@...ux.alibaba.com,
	eperezma@...hat.com,
	virtualization@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Naresh Kamboju <naresh.kamboju@...aro.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	"kernelci . org bot" <bot@...nelci.org>,
	Linux Kernel Functional Testing <lkft@...aro.org>
Subject: [PATCH] virtio_ring: fix uninitialized used value

Buildbot reports uninitialized used:

drivers/virtio/virtio_ring.c:2113:40: error: variable 'id' is
uninitialized when used here [-Werror,-Wuninitialized]
 2113 |                 BAD_RING(vq, "id %u out of range\n", id);
      |                                                      ^~
drivers/virtio/virtio_ring.c:2077:19: note: initialize the variable
'id' to silence this warning
 2077 |         u16 last_used, id, last_used_idx;
      |                          ^
      |                           = 0
1 error generated.

Fixing this by use last_used instead and drop the complete unused
variable id.

Cc: Naresh Kamboju <naresh.kamboju@...aro.org>
Cc: Randy Dunlap <rdunlap@...radead.org>
Reported-by: kernelci.org bot <bot@...nelci.org>
Reported-by: Linux Kernel Functional Testing <lkft@...aro.org>
---
 drivers/virtio/virtio_ring.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 8f9413acd4e2..7b960ce9a034 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2074,7 +2074,7 @@ static void *virtqueue_get_buf_ctx_packed_in_order(struct vring_virtqueue *vq,
 						   void **ctx)
 {
 	unsigned int num = vq->packed.vring.num;
-	u16 last_used, id, last_used_idx;
+	u16 last_used, last_used_idx;
 	bool used_wrap_counter;
 	void *ret;
 
@@ -2110,11 +2110,11 @@ static void *virtqueue_get_buf_ctx_packed_in_order(struct vring_virtqueue *vq,
 		*len = vq->packed.desc_state[last_used].total_len;
 
 	if (unlikely(last_used >= num)) {
-		BAD_RING(vq, "id %u out of range\n", id);
+		BAD_RING(vq, "id %u out of range\n", last_used);
 		return NULL;
 	}
 	if (unlikely(!vq->packed.desc_state[last_used].data)) {
-		BAD_RING(vq, "id %u is not a head!\n", id);
+		BAD_RING(vq, "id %u is not a head!\n", last_used);
 		return NULL;
 	}
 
-- 
2.39.5