linux-kernel - [PATCH 03/15] mwifiex: avoid -Wstringop-overflow warning

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Date:   Thu, 30 Apr 2020 23:30:45 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     linux-kernel@...r.kernel.org,
        Amitkumar Karwar <amitkarwar@...il.com>,
        Ganapathi Bhat <ganapathi.bhat@....com>,
        Xinming Hu <huxinming820@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Bing Zhao <bzhao@...vell.com>,
        Marc Yang <yangyang@...vell.com>,
        Ramesh Radhakrishnan <rramesh@...vell.com>,
        Kiran Divekar <dkiran@...vell.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Nishant Sarmukadam <nishants@...vell.com>,
        Amitkumar Karwar <akarwar@...vell.com>,
        Yogesh Ashok Powar <yogeshp@...vell.com>,
        Frank Huang <frankh@...vell.com>,
        "John W. Linville" <linville@...driver.com>,
        Cathy Luo <xiaohua.luo@....com>, James Cao <zheng.cao@....com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH 03/15] mwifiex: avoid -Wstringop-overflow warning

gcc-10 reports a warning for mwifiex_cmd_802_11_key_material_v1:

drivers/net/wireless/marvell/mwifiex/sta_cmd.c: In function 'mwifiex_cmd_802_11_key_material_v1':
cc1: warning: writing 16 bytes into a region of size 0 [-Wstringop-overflow=]
In file included from drivers/net/wireless/marvell/mwifiex/sta_cmd.c:23:
drivers/net/wireless/marvell/mwifiex/fw.h:993:9: note: at offset 0 to object 'action' with size 2 declared here
  993 |  __le16 action;
      |         ^~~~~~

As the warning makes no sense, I reported it as a bug for gcc. In the
meantime using a temporary pointer for the key data makes the code easier
to read and stops the warning.

Fixes: 5e6e3a92b9a4 ("wireless: mwifiex: initial commit for Marvell mwifiex driver")
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94881
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 .../net/wireless/marvell/mwifiex/sta_cmd.c    | 39 ++++++++-----------
 1 file changed, 16 insertions(+), 23 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/sta_cmd.c b/drivers/net/wireless/marvell/mwifiex/sta_cmd.c
index 0bd93f26bd7f..8bd355d7974e 100644
--- a/drivers/net/wireless/marvell/mwifiex/sta_cmd.c
+++ b/drivers/net/wireless/marvell/mwifiex/sta_cmd.c
@@ -853,43 +853,36 @@ mwifiex_cmd_802_11_key_material_v1(struct mwifiex_private *priv,
 		memset(&key_material->key_param_set, 0,
 		       sizeof(struct mwifiex_ie_type_key_param_set));
 	if (enc_key->is_wapi_key) {
+		struct mwifiex_ie_type_key_param_set *set;
+
 		mwifiex_dbg(priv->adapter, INFO, "info: Set WAPI Key\n");
-		key_material->key_param_set.key_type_id =
-						cpu_to_le16(KEY_TYPE_ID_WAPI);
+		set = &key_material->key_param_set;
+		set->key_type_id = cpu_to_le16(KEY_TYPE_ID_WAPI);
 		if (cmd_oid == KEY_INFO_ENABLED)
-			key_material->key_param_set.key_info =
-						cpu_to_le16(KEY_ENABLED);
+			set->key_info = cpu_to_le16(KEY_ENABLED);
 		else
-			key_material->key_param_set.key_info =
-						cpu_to_le16(!KEY_ENABLED);
+			set->key_info = cpu_to_le16(!KEY_ENABLED);
 
-		key_material->key_param_set.key[0] = enc_key->key_index;
+		set->key[0] = enc_key->key_index;
 		if (!priv->sec_info.wapi_key_on)
-			key_material->key_param_set.key[1] = 1;
+			set->key[1] = 1;
 		else
 			/* set 0 when re-key */
-			key_material->key_param_set.key[1] = 0;
+			set->key[1] = 0;
 
 		if (!is_broadcast_ether_addr(enc_key->mac_addr)) {
 			/* WAPI pairwise key: unicast */
-			key_material->key_param_set.key_info |=
-				cpu_to_le16(KEY_UNICAST);
+			set->key_info |= cpu_to_le16(KEY_UNICAST);
 		} else {	/* WAPI group key: multicast */
-			key_material->key_param_set.key_info |=
-				cpu_to_le16(KEY_MCAST);
+			set->key_info |= cpu_to_le16(KEY_MCAST);
 			priv->sec_info.wapi_key_on = true;
 		}
 
-		key_material->key_param_set.type =
-					cpu_to_le16(TLV_TYPE_KEY_MATERIAL);
-		key_material->key_param_set.key_len =
-						cpu_to_le16(WAPI_KEY_LEN);
-		memcpy(&key_material->key_param_set.key[2],
-		       enc_key->key_material, enc_key->key_len);
-		memcpy(&key_material->key_param_set.key[2 + enc_key->key_len],
-		       enc_key->pn, PN_LEN);
-		key_material->key_param_set.length =
-			cpu_to_le16(WAPI_KEY_LEN + KEYPARAMSET_FIXED_LEN);
+		set->type = cpu_to_le16(TLV_TYPE_KEY_MATERIAL);
+		set->key_len = cpu_to_le16(WAPI_KEY_LEN);
+		memcpy(&set->key[2], enc_key->key_material, enc_key->key_len);
+		memcpy(&set->key[2 + enc_key->key_len], enc_key->pn, PN_LEN);
+		set->length = cpu_to_le16(WAPI_KEY_LEN + KEYPARAMSET_FIXED_LEN);
 
 		key_param_len = (WAPI_KEY_LEN + KEYPARAMSET_FIXED_LEN) +
 				 sizeof(struct mwifiex_ie_types_header);
-- 
2.26.0