From fa5054c4bb994311278d4a99cccf09be69296177 Mon Sep 17 00:00:00 2001 From: Olivier Matz Date: Wed, 7 Oct 2020 14:53:18 +0200 Subject: [PATCH] vhost: fix external mbuf creation In virtio_dev_extbuf_alloc(), the shinfo structure used to store the reference counter and the free callback of the external buffer is by default stored inside the mbuf data. This is wrong because the mbuf (and its data) can be freed before the external buffer, for instance in the following situation: pkt2 = rte_pktmbuf_alloc(mp); rte_pktmbuf_attach(pkt2, pkt); rte_pktmbuf_free(pkt); After this, pkt is freed, but it still contains shinfo, which is referenced by pkt2. Fix this by always storing the shinfo beside the external buffer. Fixes: c3ff0ac70acb ("vhost: improve performance by supporting large buffer") Cc: stable@dpdk.org Signed-off-by: Olivier Matz Reviewed-by: Maxime Coquelin --- lib/librte_vhost/virtio_net.c | 30 ++++++++---------------------- 1 file changed, 8 insertions(+), 22 deletions(-) diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index 0a0bea1a5a..008f5ceb04 100644 --- a/lib/librte_vhost/virtio_net.c +++ b/lib/librte_vhost/virtio_net.c @@ -2098,16 +2098,8 @@ virtio_dev_extbuf_alloc(struct rte_mbuf *pkt, uint32_t size) rte_iova_t iova; void *buf; - /* Try to use pkt buffer to store shinfo to reduce the amount of memory - * required, otherwise store shinfo in the new buffer. - */ - if (rte_pktmbuf_tailroom(pkt) >= sizeof(*shinfo)) - shinfo = rte_pktmbuf_mtod(pkt, - struct rte_mbuf_ext_shared_info *); - else { - total_len += sizeof(*shinfo) + sizeof(uintptr_t); - total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t)); - } + total_len += sizeof(*shinfo) + sizeof(uintptr_t); + total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t)); if (unlikely(total_len > UINT16_MAX)) return -ENOSPC; @@ -2118,18 +2110,12 @@ virtio_dev_extbuf_alloc(struct rte_mbuf *pkt, uint32_t size) return -ENOMEM; /* Initialize shinfo */ - if (shinfo) { - shinfo->free_cb = virtio_dev_extbuf_free; - shinfo->fcb_opaque = buf; - rte_mbuf_ext_refcnt_set(shinfo, 1); - } else { - shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len, - virtio_dev_extbuf_free, buf); - if (unlikely(shinfo == NULL)) { - rte_free(buf); - VHOST_LOG_DATA(ERR, "Failed to init shinfo\n"); - return -1; - } + shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len, + virtio_dev_extbuf_free, buf); + if (unlikely(shinfo == NULL)) { + rte_free(buf); + VHOST_LOG_DATA(ERR, "Failed to init shinfo\n"); + return -1; } iova = rte_malloc_virt2iova(buf); -- 2.20.1