linux-kernel - [PATCH] virtio_ring: Fix mem leak with vring_new

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Message-ID: <20200224212643.30672-1-s-anna@ti.com>
Date:   Mon, 24 Feb 2020 15:26:43 -0600
From:   Suman Anna <s-anna@...com>
To:     "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>
CC:     Tiwei Bie <tiwei.bie@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        <virtualization@...ts.linux-foundation.org>,
        <linux-kernel@...r.kernel.org>, <linux-remoteproc@...r.kernel.org>,
        Suman Anna <s-anna@...com>
Subject: [PATCH] virtio_ring: Fix mem leak with vring_new_virtqueue()

The functions vring_new_virtqueue() and __vring_new_virtqueue() are used
with split rings, and any allocations within these functions are managed
outside of the .we_own_ring flag. The commit cbeedb72b97a ("virtio_ring:
allocate desc state for split ring separately") allocates the desc state
within the __vring_new_virtqueue() but frees it only when the .we_own_ring
flag is set. This leads to a memory leak when freeing such allocated
virtqueues with the vring_del_virtqueue() function.

Fix this by moving the desc_state free code outside the flag and only
for split rings. Issue was discovered during testing with remoteproc
and virtio_rpmsg.

Fixes: cbeedb72b97a ("virtio_ring: allocate desc state for split ring separately")
Signed-off-by: Suman Anna <s-anna@...com>
---
 drivers/virtio/virtio_ring.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 867c7ebd3f10..58b96baa8d48 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2203,10 +2203,10 @@ void vring_del_virtqueue(struct virtqueue *_vq)
 					 vq->split.queue_size_in_bytes,
 					 vq->split.vring.desc,
 					 vq->split.queue_dma_addr);
-
-			kfree(vq->split.desc_state);
 		}
 	}
+	if (!vq->packed_ring)
+		kfree(vq->split.desc_state);
 	list_del(&_vq->list);
 	kfree(vq);
 }
-- 
2.23.0