[PATCH 07/64] staging: rtl8192e: Use struct_group() for memcpy() region

Kees Cook
2021-07-27T21:00:27Z

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() around members addr1, addr2, and addr3 in struct
rtllib_hdr_4addr, and members qui, qui_type, qui_subtype, version,
and ac_info in struct rtllib_qos_information_element, 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 addr1 and qui.

"pahole" shows no size nor member offset changes to struct
rtllib_hdr_4addr nor struct rtllib_qos_information_element. "objdump -d"
shows no meaningful object code changes (i.e. only source line number
induced differences and optimizations).

Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/staging/rtl8192e/rtllib.h | 20 ++++++++++++--------
drivers/staging/rtl8192e/rtllib_crypt_ccmp.c | 3 ++-
drivers/staging/rtl8192e/rtllib_rx.c | 8 ++++----
3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/rtl8192e/rtllib.h b/drivers/staging/rtl8192e/rtllib.h
index c6f8b772335c..547579070a82 100644
--- a/drivers/staging/rtl8192e/rtllib.h
+++ b/drivers/staging/rtl8192e/rtllib.h
@@ -759,9 +759,11 @@ struct rtllib_hdr_3addr {
struct rtllib_hdr_4addr {
__le16 frame_ctl;
__le16 duration_id;
- u8 addr1[ETH_ALEN];
- u8 addr2[ETH_ALEN];
- u8 addr3[ETH_ALEN];
+ struct_group(addrs,
+ u8 addr1[ETH_ALEN];
+ u8 addr2[ETH_ALEN];
+ u8 addr3[ETH_ALEN];
+ );
__le16 seq_ctl;
u8 addr4[ETH_ALEN];
u8 payload[];
@@ -921,11 +923,13 @@ union frameqos {
struct rtllib_qos_information_element {
u8 elementID;
u8 length;
- u8 qui[QOS_OUI_LEN];
- u8 qui_type;
- u8 qui_subtype;
- u8 version;
- u8 ac_info;
+ struct_group(data,
+ u8 qui[QOS_OUI_LEN];
+ u8 qui_type;
+ u8 qui_subtype;
+ u8 version;
+ u8 ac_info;
+ );
} __packed;

struct rtllib_qos_ac_parameter {
diff --git a/drivers/staging/rtl8192e/rtllib_crypt_ccmp.c b/drivers/staging/rtl8192e/rtllib_crypt_ccmp.c
index b60e2a109ce4..66b3a13fced7 100644
--- a/drivers/staging/rtl8192e/rtllib_crypt_ccmp.c
+++ b/drivers/staging/rtl8192e/rtllib_crypt_ccmp.c
@@ -133,7 +133,8 @@ static int ccmp_init_iv_and_aad(struct rtllib_hdr_4addr *hdr,
pos = (u8 *) hdr;
aad[0] = pos[0] & 0x8f;
aad[1] = pos[1] & 0xc7;
- memcpy(aad + 2, hdr->addr1, 3 * ETH_ALEN);
+ BUILD_BUG_ON(sizeof(hdr->addrs) != (3 * ETH_ALEN));
+ memcpy(aad + 2, &hdr->addrs, 3 * ETH_ALEN);
pos = (u8 *) &hdr->seq_ctl;
aad[20] = pos[0] & 0x0f;
aad[21] = 0; /* all bits masked */
diff --git a/drivers/staging/rtl8192e/rtllib_rx.c b/drivers/staging/rtl8192e/rtllib_rx.c
index c2209c033838..9c4b686d2756 100644
--- a/drivers/staging/rtl8192e/rtllib_rx.c
+++ b/drivers/staging/rtl8192e/rtllib_rx.c
@@ -1576,13 +1576,13 @@ static int rtllib_read_qos_param_element(struct rtllib_qos_parameter_info
*info_element)
{
int ret = 0;
- u16 size = sizeof(struct rtllib_qos_parameter_info) - 2;
+ u16 size = sizeof(element_param->info_element.data);

if ((info_element == NULL) || (element_param == NULL))
return -1;

if (info_element->id == QOS_ELEMENT_ID && info_element->len == size) {
- memcpy(element_param->info_element.qui, info_element->data,
+ memcpy(&element_param->info_element.data, info_element->data,
info_element->len);
element_param->info_element.elementID = info_element->id;
element_param->info_element.length = info_element->len;
@@ -1601,7 +1601,7 @@ static int rtllib_read_qos_info_element(struct rtllib_qos_information_element
*info_element)
{
int ret = 0;
- u16 size = sizeof(struct rtllib_qos_information_element) - 2;
+ u16 size = sizeof(element_info->data);

if (element_info == NULL)
return -1;
@@ -1610,7 +1610,7 @@ static int rtllib_read_qos_info_element(struct rtllib_qos_information_element

if ((info_element->id == QOS_ELEMENT_ID) &&
(info_element->len == size)) {
- memcpy(element_info->qui, info_element->data,
+ memcpy(&element_info->data, info_element->data,
info_element->len);
element_info->elementID = info_element->id;
element_info->length = info_element->len;
--
2.30.2