[PATCH] net/memif: fix buffer overflow in zero copy Rx

[Mihai Brodschi <mihai.brodschi@broadcom.com>]

[-- Attachment #1: Type: text/plain, Size: 2684 bytes --]

rte_pktmbuf_alloc_bulk is called by the zero-copy receiver to allocate
new mbufs to be provided to the sender. The allocated mbuf pointers
are stored in a ring, but the alloc function doesn't implement index
wrap-around, so it writes past the end of the array. This results in
memory corruption and duplicate mbufs being received.

Allocate 2x the space for the mbuf ring, so that the alloc function
has a contiguous array to write to, then copy the excess entries
to the start of the array.

Fixes: 43b815d88188 ("net/memif: support zero-copy slave")
Cc: stable@dpdk.org
Signed-off-by: Mihai Brodschi <mihai.brodschi@broadcom.com>
---
  drivers/net/memif/rte_eth_memif.c | 10 +++++++++-
  1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/memif/rte_eth_memif.c 
b/drivers/net/memif/rte_eth_memif.c
index 16da22b5c6..3491c53cf1 100644
--- a/drivers/net/memif/rte_eth_memif.c
+++ b/drivers/net/memif/rte_eth_memif.c
@@ -600,6 +600,10 @@ eth_memif_rx_zc(void *queue, struct rte_mbuf 
**bufs, uint16_t nb_pkts)
  	ret = rte_pktmbuf_alloc_bulk(mq->mempool, &mq->buffers[head & mask], 
n_slots);
  	if (unlikely(ret < 0))
  		goto no_free_mbufs;
+	if (unlikely(n_slots > ring_size - (head & mask))) {
+		rte_memcpy(mq->buffers, &mq->buffers[ring_size],
+			(n_slots + (head & mask) - ring_size) * sizeof(struct rte_mbuf *));
+	}

  	while (n_slots--) {
  		s0 = head++ & mask;
@@ -1245,8 +1249,12 @@ memif_init_queues(struct rte_eth_dev *dev)
  		}
  		mq->buffers = NULL;
  		if (pmd->flags & ETH_MEMIF_FLAG_ZERO_COPY) {
+			/*
+			 * Allocate 2x ring_size to reserve a contiguous array for
+			 * rte_pktmbuf_alloc_bulk (to store allocated mbufs).
+			 */
  			mq->buffers = rte_zmalloc("bufs", sizeof(struct rte_mbuf *) *
-						  (1 << mq->log2_ring_size), 0);
+						  (1 << (mq->log2_ring_size + 1)), 0);
  			if (mq->buffers == NULL)
  				return -ENOMEM;
  		}
-- 
2.43.0

-- 
This electronic communication and the information and any files transmitted 
with it, or attached to it, are confidential and are intended solely for 
the use of the individual or entity to whom it is addressed and may contain 
information that is confidential, legally privileged, protected by privacy 
laws, or otherwise restricted from disclosure to anyone else. If you are 
not the intended recipient or the person responsible for delivering the 
e-mail to the intended recipient, you are hereby notified that any use, 
copying, distributing, dissemination, forwarding, printing, or copying of 
this e-mail is strictly prohibited. If you received this e-mail in error, 
please return the e-mail to the sender, delete it from your computer, and 
destroy any printed copy of it.

[-- Attachment #2: S/MIME Cryptographic Signature --]
[-- Type: application/pkcs7-signature, Size: 4215 bytes --]