On January 7, 2025 8:55:09 AM PST, Gal Pressman <g...@nvidia.com> wrote:
>When metadata_dst struct is allocated (using metadata_dst_alloc()), it
>reserves room for options at the end of the struct.
>
>Similar to [1], change the memcpy() to unsafe_memcpy() as it is
>guaranteed that enough room (md_size bytes) was allocated and the
>field-spanning write is intentional.
Why not just add an "options" flex array to struct ip_tunnel_info?
E.g.:
struct ip_tunnel_info {
struct ip_tunnel_key key;
struct ip_tunnel_encap encap;
#ifdef CONFIG_DST_CACHE
struct dst_cache dst_cache;
#endif
u8 options_len;
u8 mode;
u8 options[] __counted_by(options_len);
};
>
>This resolves the following warning:
> memcpy: detected field-spanning write (size 8) of single field
> "_Generic(info, const struct ip_tunnel_info * : ((const void *)((info) + 1)),
> struct ip_tunnel_info * : ((void *)((info) + 1)) )" at
> include/net/ip_tunnels.h:662 (size 0)
Then you can drop this macro and just use: info->options
Looks like you'd need to do it for all the types in struct metadata_dst, but at
least you could stop hiding it from the compiler. :)
-Kees
--
Kees Cook
