For packets received from virtio RX queue, use buddy
allocator instead of 'kmalloc()' to be able to insert
such pages to user provided vma. Single call to
'copy_from_iter()' replaced with per-page loop.
Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
---
drivers/vhost/vsock.c | 49 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 41 insertions(+), 8 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 37f0b4274113..157798985389 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -360,6 +360,9 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
struct iov_iter iov_iter;
size_t nbytes;
size_t len;
+ struct page *buf_page;
+ ssize_t pkt_len;
+ int page_idx;
if (in != 0) {
vq_err(vq, "Expected 0 input buffers, got %u\n", in);
@@ -393,20 +396,50 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
return NULL;
}
- pkt->buf = kmalloc(pkt->len, GFP_KERNEL);
- if (!pkt->buf) {
+ /* This creates memory overrun, as we allocate
+ * at least one page for each packet.
+ */
+ buf_page = alloc_pages(GFP_KERNEL, get_order(pkt->len));
+
+ if (buf_page == NULL) {
kfree(pkt);
return NULL;
}
+ pkt->buf = page_to_virt(buf_page);
pkt->buf_len = pkt->len;
- nbytes = copy_from_iter(pkt->buf, pkt->len, &iov_iter);
- if (nbytes != pkt->len) {
- vq_err(vq, "Expected %u byte payload, got %zu bytes\n",
- pkt->len, nbytes);
- virtio_transport_free_pkt(pkt);
- return NULL;
+ page_idx = 0;
+ pkt_len = pkt->len;
+
+ /* As allocated pages are not mapped, process
+ * pages one by one.
+ */
+ while (pkt_len > 0) {
+ void *mapped;
+ size_t to_copy;
+
+ mapped = kmap(buf_page + page_idx);
+
+ if (mapped == NULL) {
+ virtio_transport_free_pkt(pkt);
+ return NULL;
+ }
+
+ to_copy = min(pkt_len, ((ssize_t)PAGE_SIZE));
+
+ nbytes = copy_from_iter(mapped, to_copy, &iov_iter);
+ if (nbytes != to_copy) {
+ vq_err(vq, "Expected %zu byte payload, got %zu bytes\n",
+ to_copy, nbytes);
+ virtio_transport_free_pkt(pkt);
+ return NULL;
+ }
+
+ kunmap(mapped);
+
+ pkt_len -= to_copy;
+ page_idx++;
}
return pkt;
--
2.25.1
