openwrt/target/linux/generic/backport-5.15/733-v6.2-01-net-ethernet-mtk_eth_soc-Avoid-truncating-allocation.patch

From f3eceaed9edd7c0e0d9fb057613131f92973626f Mon Sep 17 00:00:00 2001
From: Kees Cook <[email protected]>
Date: Fri, 27 Jan 2023 14:38:54 -0800
Subject: [PATCH] net: ethernet: mtk_eth_soc: Avoid truncating allocation

There doesn't appear to be a reason to truncate the allocation used for
flow_info, so do a full allocation and remove the unused empty struct.
GCC does not like having a reference to an object that has been
partially allocated, as bounds checking may become impossible when
such an object is passed to other code. Seen with GCC 13:

../drivers/net/ethernet/mediatek/mtk_ppe.c: In function 'mtk_foe_entry_commit_subflow':
../drivers/net/ethernet/mediatek/mtk_ppe.c:623:18: warning: array subscript 'struct mtk_flow_entry[0]' is partly outside array bounds of 'unsigned char[48]' [-Warray-bounds=]
  623 |         flow_info->l2_data.base_flow = entry;
      |                  ^~

Cc: Felix Fietkau <[email protected]>
Cc: John Crispin <[email protected]>
Cc: Sean Wang <[email protected]>
Cc: Mark Lee <[email protected]>
Cc: Lorenzo Bianconi <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Matthias Brugger <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
---
 drivers/net/ethernet/mediatek/mtk_ppe.c | 3 +--
 drivers/net/ethernet/mediatek/mtk_ppe.h | 1 -
 2 files changed, 1 insertion(+), 3 deletions(-)

--- a/drivers/net/ethernet/mediatek/mtk_ppe.c
+++ b/drivers/net/ethernet/mediatek/mtk_ppe.c
@@ -621,8 +621,7 @@ mtk_foe_entry_commit_subflow(struct mtk_
 	u32 ib1_mask = mtk_get_ib1_pkt_type_mask(ppe->eth) | MTK_FOE_IB1_UDP;
 	int type;
 
-	flow_info = kzalloc(offsetof(struct mtk_flow_entry, l2_data.end),
-			    GFP_ATOMIC);
+	flow_info = kzalloc(sizeof(*flow_info), GFP_ATOMIC);
 	if (!flow_info)
 		return;
 
--- a/drivers/net/ethernet/mediatek/mtk_ppe.h
+++ b/drivers/net/ethernet/mediatek/mtk_ppe.h
@@ -279,7 +279,6 @@ struct mtk_flow_entry {
 		struct {
 			struct mtk_flow_entry *base_flow;
 			struct hlist_node list;
-			struct {} end;
 		} l2_data;
 	};
 	struct rhash_head node;