!1469 netfilter: nf_tables: prevent OOB access in nft_byteorder_eval

Merge Pull Request from: @ci-robot 
 
PR sync from: Ziyang Xuan <william.xuanziyang@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/A46YSUGPFWTYNDQDDIBLVTYQP7CWKM7I/ 
 
https://gitee.com/src-openeuler/kernel/issues/I7ISR1 
 
Link:https://gitee.com/openeuler/kernel/pulls/1469 

Reviewed-by: Yue Haibing <yuehaibing@huawei.com> 
Signed-off-by: Liu YongQiang <liuyongqiang13@huawei.com> 

net/netfilter/nft_byteorder.c

@@ -33,11 +33,11 @@ static void nft_byteorder_eval(const struct nft_expr *expr,
 	const struct nft_byteorder *priv = nft_expr_priv(expr);
 	u32 *src = &regs->data[priv->sreg];
 	u32 *dst = &regs->data[priv->dreg];
-	union { u32 u32; u16 u16; } *s, *d;
+	u16 *s16, *d16;
 	unsigned int i;
 
-	s = (void *)src;
-	d = (void *)dst;
+	s16 = (void *)src;
+	d16 = (void *)dst;
 
 	switch (priv->size) {
 	case 8: {
@@ -63,11 +63,11 @@ static void nft_byteorder_eval(const struct nft_expr *expr,
 		switch (priv->op) {
 		case NFT_BYTEORDER_NTOH:
 			for (i = 0; i < priv->len / 4; i++)
-				d[i].u32 = ntohl((__force __be32)s[i].u32);
+				dst[i] = ntohl((__force __be32)src[i]);
 			break;
 		case NFT_BYTEORDER_HTON:
 			for (i = 0; i < priv->len / 4; i++)
-				d[i].u32 = (__force __u32)htonl(s[i].u32);
+				dst[i] = (__force __u32)htonl(src[i]);
 			break;
 		}
 		break;
@@ -75,11 +75,11 @@ static void nft_byteorder_eval(const struct nft_expr *expr,
 		switch (priv->op) {
 		case NFT_BYTEORDER_NTOH:
 			for (i = 0; i < priv->len / 2; i++)
-				d[i].u16 = ntohs((__force __be16)s[i].u16);
+				d16[i] = ntohs((__force __be16)s16[i]);
 			break;
 		case NFT_BYTEORDER_HTON:
 			for (i = 0; i < priv->len / 2; i++)
-				d[i].u16 = (__force __u16)htons(s[i].u16);
+				d16[i] = (__force __u16)htons(s16[i]);
 			break;
 		}
 		break;