In an effort to avoid open-coded arithmetic in the kernel, use the
struct_size() helper instead of open-coded calculation.
Link: https://github.com/KSPP/linux/issues/160
Signed-off-by: Xiu Jianfeng <[email protected]>
---
kernel/bpf/local_storage.c | 3 +--
kernel/bpf/reuseport_array.c | 6 +-----
2 files changed, 2 insertions(+), 7 deletions(-)
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 035e9e3a7132..23f7f9d08a62 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -163,8 +163,7 @@ static int cgroup_storage_update_elem(struct bpf_map *map, void *key,
return 0;
}
- new = bpf_map_kmalloc_node(map, sizeof(struct bpf_storage_buffer) +
- map->value_size,
+ new = bpf_map_kmalloc_node(map, struct_size(new, data, map->value_size),
__GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN,
map->numa_node);
if (!new)
diff --git a/kernel/bpf/reuseport_array.c b/kernel/bpf/reuseport_array.c
index 93a55391791a..556a769b5b80 100644
--- a/kernel/bpf/reuseport_array.c
+++ b/kernel/bpf/reuseport_array.c
@@ -152,16 +152,12 @@ static struct bpf_map *reuseport_array_alloc(union bpf_attr *attr)
{
int numa_node = bpf_map_attr_numa_node(attr);
struct reuseport_array *array;
- u64 array_size;
if (!bpf_capable())
return ERR_PTR(-EPERM);
- array_size = sizeof(*array);
- array_size += (u64)attr->max_entries * sizeof(struct sock *);
-
/* allocate all map elements and zero-initialize them */
- array = bpf_map_area_alloc(array_size, numa_node);
+ array = bpf_map_area_alloc(struct_size(array, ptrs, attr->max_entries), numa_node);
if (!array)
return ERR_PTR(-ENOMEM);
--
2.17.1
On 12/20/21 3:30 AM, Xiu Jianfeng wrote:
> In an effort to avoid open-coded arithmetic in the kernel, use the
> struct_size() helper instead of open-coded calculation.
>
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Xiu Jianfeng <[email protected]>
Ack with a minor comments below.
Acked-by: Yonghong Song <[email protected]>
> ---
> kernel/bpf/local_storage.c | 3 +--
> kernel/bpf/reuseport_array.c | 6 +-----
> 2 files changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
> index 035e9e3a7132..23f7f9d08a62 100644
> --- a/kernel/bpf/local_storage.c
> +++ b/kernel/bpf/local_storage.c
> @@ -163,8 +163,7 @@ static int cgroup_storage_update_elem(struct bpf_map *map, void *key,
> return 0;
> }
>
> - new = bpf_map_kmalloc_node(map, sizeof(struct bpf_storage_buffer) +
> - map->value_size,
> + new = bpf_map_kmalloc_node(map, struct_size(new, data, map->value_size),
> __GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN,
> map->numa_node);
> if (!new)
> diff --git a/kernel/bpf/reuseport_array.c b/kernel/bpf/reuseport_array.c
> index 93a55391791a..556a769b5b80 100644
> --- a/kernel/bpf/reuseport_array.c
> +++ b/kernel/bpf/reuseport_array.c
> @@ -152,16 +152,12 @@ static struct bpf_map *reuseport_array_alloc(union bpf_attr *attr)
> {
> int numa_node = bpf_map_attr_numa_node(attr);
> struct reuseport_array *array;
> - u64 array_size;
>
> if (!bpf_capable())
> return ERR_PTR(-EPERM);
>
> - array_size = sizeof(*array);
> - array_size += (u64)attr->max_entries * sizeof(struct sock *);
We have u64 type conversion here while struct_size used type 'size_t'.
So we won't have problems for 64bit system. But for 32bit system, we may
have a slight different behavior here as the current code can return a
u64 value and the struct_size(...) returns a size_t type value with max
value SIZE_MAX.
In __bpf_map_area_alloc() we have a check:
if (size >= SIZE_MAX)
return NULL;
so we should be fine for 32bit system.
> -
> /* allocate all map elements and zero-initialize them */
> - array = bpf_map_area_alloc(array_size, numa_node);
> + array = bpf_map_area_alloc(struct_size(array, ptrs, attr->max_entries), numa_node);
> if (!array)
> return ERR_PTR(-ENOMEM);
>
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <[email protected]>:
On Mon, 20 Dec 2021 19:30:48 +0800 you wrote:
> In an effort to avoid open-coded arithmetic in the kernel, use the
> struct_size() helper instead of open-coded calculation.
>
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Xiu Jianfeng <[email protected]>
> ---
> kernel/bpf/local_storage.c | 3 +--
> kernel/bpf/reuseport_array.c | 6 +-----
> 2 files changed, 2 insertions(+), 7 deletions(-)
Here is the summary with links:
- [bpf-next] bpf: Use struct_size() helper
https://git.kernel.org/bpf/bpf-next/c/0dd668d2080c
You are awesome, thank you!
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