[PATCH net] net: mana: validate rx_req_idx to prevent out-of-bounds array access

[PATCH net] net: mana: validate rx_req_idx to prevent out-of-bounds array access

[Aditya Garg]

In mana_hwc_rx_event_handler(), rx_req_idx is derived from
sge->address in DMA-coherent memory. In Confidential VMs
(SEV-SNP/TDX), this memory is shared unencrypted and HW can modify
WQE contents at any time. No bounds check exists on rx_req_idx,
which can lead to an out-of-bounds access into reqs[].

Add bounds check on rx_req_idx in mana_hwc_rx_event_handler() before
using it to index the reqs[] array.

Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)")
Signed-off-by: Aditya Garg <gargaditya@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 drivers/net/ethernet/microsoft/mana/hw_channel.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/microsoft/mana/hw_channel.c b/drivers/net/ethernet/microsoft/mana/hw_channel.c
index dbbde0fa57e7..a60f733d1a07 100644
--- a/drivers/net/ethernet/microsoft/mana/hw_channel.c
+++ b/drivers/net/ethernet/microsoft/mana/hw_channel.c
@@ -266,6 +266,12 @@ static void mana_hwc_rx_event_handler(void *ctx, u32 gdma_rxq_id,
 	rq_base_addr = hwc_rxq->msg_buf->mem_info.dma_handle;
 	rx_req_idx = (sge->address - rq_base_addr) / hwc->max_req_msg_size;
 
+	if (rx_req_idx >= hwc_rxq->msg_buf->num_reqs) {
+		dev_err(hwc->dev, "HWC RX: wrong rx_req_idx=%llu, num_reqs=%u\n",
+			rx_req_idx, hwc_rxq->msg_buf->num_reqs);
+		return;
+	}
+
 	rx_req = &hwc_rxq->msg_buf->reqs[rx_req_idx];
 	resp = (struct gdma_resp_hdr *)rx_req->buf_va;
 
-- 
2.43.0