linux-hardening - [PATCH 15/64] ipw2x00: Use struct

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Date:   Tue, 27 Jul 2021 13:58:06 -0700
From:   Kees Cook <keescook@...omium.org>
To:     linux-hardening@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Keith Packard <keithpac@...zon.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-staging@...ts.linux.dev, linux-block@...r.kernel.org,
        linux-kbuild@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: [PATCH 15/64] ipw2x00: Use struct_group() for memcpy() region

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field array bounds checking for memcpy(), memmove(), and memset(),
avoid intentionally writing across neighboring fields.

Use struct_group() in struct libipw_qos_information_element around
members qui, qui_type, qui_subtype, version, and ac_info, 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 qui.

"pahole" shows no size nor member offset changes to struct
libipw_qos_information_element.

Additionally corrects the size in libipw_read_qos_param_element() as
it was testing the wrong structure size (it should have been struct
libipw_qos_information_element, not struct libipw_qos_parameter_info).

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/net/wireless/intel/ipw2x00/libipw.h    | 12 +++++++-----
 drivers/net/wireless/intel/ipw2x00/libipw_rx.c |  8 ++++----
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/intel/ipw2x00/libipw.h b/drivers/net/wireless/intel/ipw2x00/libipw.h
index 7964ef7d15f0..4006a0db2eea 100644
--- a/drivers/net/wireless/intel/ipw2x00/libipw.h
+++ b/drivers/net/wireless/intel/ipw2x00/libipw.h
@@ -537,11 +537,13 @@ struct libipw_txb {
 struct libipw_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 libipw_qos_ac_parameter {
diff --git a/drivers/net/wireless/intel/ipw2x00/libipw_rx.c b/drivers/net/wireless/intel/ipw2x00/libipw_rx.c
index 5a2a723e480b..75cc3cab4992 100644
--- a/drivers/net/wireless/intel/ipw2x00/libipw_rx.c
+++ b/drivers/net/wireless/intel/ipw2x00/libipw_rx.c
@@ -948,13 +948,13 @@ static int libipw_read_qos_param_element(struct libipw_qos_parameter_info
 					    *info_element)
 {
 	int ret = 0;
-	u16 size = sizeof(struct libipw_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;
@@ -975,7 +975,7 @@ static int libipw_read_qos_info_element(struct
 					   *info_element)
 {
 	int ret = 0;
-	u16 size = sizeof(struct libipw_qos_information_element) - 2;
+	u16 size = sizeof(element_info->data);
 
 	if (element_info == NULL)
 		return -1;
@@ -983,7 +983,7 @@ static int libipw_read_qos_info_element(struct
 		return -1;
 
 	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