[PATCH 15/32] 802/garp: Use mem_to_flex_dup() with struct garp_attr

Kees Cook
2022-05-04T01:52:43Z

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: Hulk Robot <hulkci@huawei.com>
Cc: Yang Yingliang <yangyingliang@huawei.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
include/net/garp.h | 4 ++--
net/802/garp.c | 9 +++------
2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/include/net/garp.h b/include/net/garp.h
index 4d9a0c6a2e5f..ec087ae534e7 100644
--- a/include/net/garp.h
+++ b/include/net/garp.h
@@ -80,8 +80,8 @@ struct garp_attr {
struct rb_node node;
enum garp_applicant_state state;
u8 type;
- u8 dlen;
- unsigned char data[];
+ DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(u8, dlen);
+ DECLARE_FLEX_ARRAY_ELEMENTS(unsigned char, data);
};

enum garp_applications {
diff --git a/net/802/garp.c b/net/802/garp.c
index f6012f8e59f0..72743ed00a54 100644
--- a/net/802/garp.c
+++ b/net/802/garp.c
@@ -168,7 +168,7 @@ static struct garp_attr *garp_attr_create(struct garp_applicant *app,
const void *data, u8 len, u8 type)
{
struct rb_node *parent = NULL, **p = &app->gid.rb_node;
- struct garp_attr *attr;
+ struct garp_attr *attr = NULL;
int d;

while (*p) {
@@ -184,13 +184,10 @@ static struct garp_attr *garp_attr_create(struct garp_applicant *app,
return attr;
}
}
- attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
- if (!attr)
- return attr;
+ if (mem_to_flex_dup(&attr, data, len, GFP_ATOMIC))
+ return NULL;
attr->state = GARP_APPLICANT_VO;
attr->type = type;
- attr->dlen = len;
- memcpy(attr->data, data, len);

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