[PATCH 16/32] 802/mrp: Use mem_to_flex_dup() with struct mrp_attr

Kees Cook
2022-05-04T01:51:24Z

As part of the work to perform bounds checking on all memcpy() uses,
replace the open-coded a deserialization of bytes out of memory into a
trailing flexible array by using a flex_array.h helper to perform the
allocation, bounds checking, and copying.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Yang Yingliang <yangyingliang@huawei.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
include/net/mrp.h | 4 ++--
net/802/mrp.c | 9 +++------
2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/include/net/mrp.h b/include/net/mrp.h
index 1c308c034e1a..211670bb46f2 100644
--- a/include/net/mrp.h
+++ b/include/net/mrp.h
@@ -91,8 +91,8 @@ struct mrp_attr {
struct rb_node node;
enum mrp_applicant_state state;
u8 type;
- u8 len;
- unsigned char value[];
+ DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(u8, len);
+ DECLARE_FLEX_ARRAY_ELEMENTS(unsigned char, value);
};

enum mrp_applications {
diff --git a/net/802/mrp.c b/net/802/mrp.c
index 35e04cc5390c..8b9b2e685a42 100644
--- a/net/802/mrp.c
+++ b/net/802/mrp.c
@@ -257,7 +257,7 @@ static struct mrp_attr *mrp_attr_create(struct mrp_applicant *app,
const void *value, u8 len, u8 type)
{
struct rb_node *parent = NULL, **p = &app->mad.rb_node;
- struct mrp_attr *attr;
+ struct mrp_attr *attr = NULL;
int d;

while (*p) {
@@ -273,13 +273,10 @@ static struct mrp_attr *mrp_attr_create(struct mrp_applicant *app,
return attr;
}
}
- attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
- if (!attr)
- return attr;
+ if (mem_to_flex_dup(&attr, value, len, GFP_ATOMIC))
+ return NULL;
attr->state = MRP_APPLICANT_VO;
attr->type = type;
- attr->len = len;
- memcpy(attr->value, value, len);

rb_link_node(&attr->node, parent, p);
rb_insert_color(&attr->node, &app->mad);
--
2.32.0