[PATCH 1/1] misc/vmw_vmci: fix filling of the msg and msg_payload in dg_info struct

[kovalev@altlinux.org]

From: Vasiliy Kovalev <kovalev@altlinux.org>

Fix "detected field-spanning write" of memcpy warning that is issued by
the tracking mechanism __fortify_memcpy_chk, added 2021-04-20
(f68f2ff91512c199ec24883001245912afc17873 fortify: Detect struct member overflows in memcpy() at compile-time)

Fixes: a110b7ebb9c674 ("VMCI: datagram implementation.")
Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org>
---
 drivers/misc/vmw_vmci/vmci_datagram.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/vmw_vmci/vmci_datagram.c b/drivers/misc/vmw_vmci/vmci_datagram.c
index f50d22882476f9..27853b31e288b1 100644
--- a/drivers/misc/vmw_vmci/vmci_datagram.c
+++ b/drivers/misc/vmw_vmci/vmci_datagram.c
@@ -234,7 +234,10 @@ static int dg_dispatch_as_host(u32 context_id, struct vmci_datagram *dg)
 
 			dg_info->in_dg_host_queue = true;
 			dg_info->entry = dst_entry;
-			memcpy(&dg_info->msg, dg, dg_size);
+			memcpy(&dg_info->msg, dg, VMCI_DG_HEADERSIZE);
+			if (dg->payload_size) {
+				memcpy(dg_info->msg_payload, VMCI_DG_PAYLOAD(dg), dg->payload_size);
+			}
 
 			INIT_WORK(&dg_info->work, dg_delayed_dispatch);
 			schedule_work(&dg_info->work);
@@ -377,7 +380,10 @@ int vmci_datagram_invoke_guest_handler(struct vmci_datagram *dg)
 
 		dg_info->in_dg_host_queue = false;
 		dg_info->entry = dst_entry;
-		memcpy(&dg_info->msg, dg, VMCI_DG_SIZE(dg));
+		memcpy(&dg_info->msg, dg, VMCI_DG_HEADERSIZE);
+		if (dg->payload_size) {
+			memcpy(dg_info->msg_payload, VMCI_DG_PAYLOAD(dg), dg->payload_size);
+		}
 
 		INIT_WORK(&dg_info->work, dg_delayed_dispatch);
 		schedule_work(&dg_info->work);
-- 
2.33.8