[PATCH 2/2] staging: octeon: fix out-of-bounds reads in tx path

[Ayush Mukkanwar <ayushmukkanwar@gmail.com>]

1. cvm_oct_xmit() and cvm_oct_xmit_pow() blindly trust
skb->protocol == htons(ETH_P_IP) and dereference the IP header
without verifying if the packet is long enough or if the header
is in the linear skb data area.
Fix by checking if skb_headlen is larger than
skb_network_offset + size of ip header.

2. cvm_oct_xmit_pow() copies packet data into a fixed size
hardware buffer using a hardcoded memcpy() size. If a packet
is smaller than it, memcpy() will read past the end of the
skb buffer. Fix this by using min_t() so that it does not read
past the end of the skb.

Fixes: 80ff0fd3ab64 ("Staging: Add octeon-ethernet driver files.")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/message/20260615172734.42038-1-ayushmukkanwar%40gmail.com
Signed-off-by: Ayush Mukkanwar <ayushmukkanwar@gmail.com>
---
Note: This patch has only been compile tested. No runtime testing was
performed as I do not have access to Octeon hardware.

 drivers/staging/octeon/ethernet-tx.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/octeon/ethernet-tx.c b/drivers/staging/octeon/ethernet-tx.c
index 5e536827f87a..452bc9fc8a5d 100644
--- a/drivers/staging/octeon/ethernet-tx.c
+++ b/drivers/staging/octeon/ethernet-tx.c
@@ -361,6 +361,8 @@ netdev_tx_t cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	/* Check if we can use the hardware checksumming */
 	if ((skb->protocol == htons(ETH_P_IP)) &&
+		(skb_network_offset(skb) >= 0) &&
+		(skb_network_offset(skb) + sizeof(struct iphdr) <= skb_headlen(skb)) &&
 	    (ip_hdr(skb)->version == 4) &&
 	    (ip_hdr(skb)->ihl == 5) &&
 	    ((ip_hdr(skb)->frag_off == 0) ||
@@ -571,6 +573,14 @@ netdev_tx_t cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev)
 	work->packet_ptr.s.back = (copy_location - packet_buffer) >> 7;
 
 	if (skb->protocol == htons(ETH_P_IP)) {
+		if (unlikely(!pskb_may_pull(skb, ETH_HLEN + sizeof(struct iphdr)))) {
+			cvmx_fpa_free(packet_buffer, CVMX_FPA_PACKET_POOL, 0);
+			cvmx_fpa_free(work, CVMX_FPA_WQE_POOL, 1);
+			dev->stats.tx_dropped++;
+			dev_kfree_skb_any(skb);
+			return NETDEV_TX_OK;
+		}
+
 		work->word2.s.ip_offset = 14;
 		work->word2.s.tcp_or_udp =
 		    (ip_hdr(skb)->protocol == IPPROTO_TCP) ||
@@ -587,7 +597,7 @@ netdev_tx_t cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev)
 		 * does.
 		 */
 		memcpy(work->packet_data, skb->data + 10,
-		       sizeof(work->packet_data));
+		       min_t(unsigned int, skb->len - 10, sizeof(work->packet_data)));
 	} else {
 		work->word2.snoip.is_rarp = skb->protocol == htons(ETH_P_RARP);
 		work->word2.snoip.is_arp = skb->protocol == htons(ETH_P_ARP);
@@ -596,7 +606,8 @@ netdev_tx_t cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev)
 		work->word2.snoip.is_mcast =
 		    (skb->pkt_type == PACKET_MULTICAST);
 		work->word2.snoip.not_IP = 1;	/* IP was done up above */
-		memcpy(work->packet_data, skb->data, sizeof(work->packet_data));
+		memcpy(work->packet_data, skb->data,
+		       min_t(unsigned int, skb->len, sizeof(work->packet_data)));
 	}
 
 	/* Submit the packet to the POW */
-- 
2.54.0