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net/mlx5e: Use struct_group() for memcpy() region

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In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring fields.

Use struct_group() in struct vlan_ethhdr around members h_dest and
h_source, so they can be referenced together. This will allow memcpy()
and sizeof() to more easily reason about sizes, improve readability,
and avoid future warnings about writing beyond the end of h_dest.

"pahole" shows no size nor member offset changes to struct vlan_ethhdr.
"objdump -d" shows no object code changes.

Fixes: 34802a42b3 ("net/mlx5e: Do not modify the TX SKB")
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
This commit is contained in:
Kees Cook 2022-01-24 09:22:41 -08:00 committed by Saeed Mahameed
parent 5b209d1a22
commit 6d5c900eb6
2 changed files with 5 additions and 3 deletions
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2
drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
View File

@ -208,7 +208,7 @@ static inline void mlx5e_insert_vlan(void *start, struct sk_buff *skb, u16 ihs)
int cpy1_sz = 2 * ETH_ALEN;
int cpy2_sz = ihs - cpy1_sz;
memcpy(vhdr, skb->data, cpy1_sz);
memcpy(&vhdr->addrs, skb->data, cpy1_sz);
vhdr->h_vlan_proto = skb->vlan_proto;
vhdr->h_vlan_TCI = cpu_to_be16(skb_vlan_tag_get(skb));
memcpy(&vhdr->h_vlan_encapsulated_proto, skb->data + cpy1_sz, cpy2_sz);

6
include/linux/if_vlan.h
View File

@ -46,8 +46,10 @@ struct vlan_hdr {
* @h_vlan_encapsulated_proto: packet type ID or len
*/
struct vlan_ethhdr {
unsigned char h_dest[ETH_ALEN];
unsigned char h_source[ETH_ALEN];
struct_group(addrs,
unsigned char h_dest[ETH_ALEN];
unsigned char h_source[ETH_ALEN];
);
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
__be16 h_vlan_encapsulated_proto;