linux-kernel - [PATCH] wifi: mt76: mt7996: Initialize hdr before passing to skb_put

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Message-Id: <20250715-mt7996-fix-uninit-const-pointer-v1-1-b5d8d11d7b78@kernel.org>
Date: Tue, 15 Jul 2025 15:33:25 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Felix Fietkau <nbd@....name>, Lorenzo Bianconi <lorenzo@...nel.org>, 
 Ryder Lee <ryder.lee@...iatek.com>
Cc: Shayne Chen <shayne.chen@...iatek.com>, 
 Sean Wang <sean.wang@...iatek.com>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
 llvm@...ts.linux.dev, stable@...r.kernel.org, 
 Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH] wifi: mt76: mt7996: Initialize hdr before passing to
 skb_put_data()

A new warning in clang [1] points out a couple of places where a hdr
variable is not initialized then passed along to skb_put_data().

  drivers/net/wireless/mediatek/mt76/mt7996/mcu.c:1894:21: warning: variable 'hdr' is uninitialized when passed as a const pointer argument here [-Wuninitialized-const-pointer]
   1894 |         skb_put_data(skb, &hdr, sizeof(hdr));
        |                            ^~~
  drivers/net/wireless/mediatek/mt76/mt7996/mcu.c:3386:21: warning: variable 'hdr' is uninitialized when passed as a const pointer argument here [-Wuninitialized-const-pointer]
   3386 |         skb_put_data(skb, &hdr, sizeof(hdr));
        |                            ^~~

Zero initialize these headers as done in other places in the driver when
there is nothing stored in the header.

Cc: stable@...r.kernel.org
Fixes: 98686cd21624 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Link: https://github.com/llvm/llvm-project/commit/00dacf8c22f065cb52efb14cd091d441f19b319e [1]
Closes: https://github.com/ClangBuiltLinux/linux/issues/2104
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7996/mcu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
index 994526c65bfc..640abb4dce7f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
@@ -1879,8 +1879,8 @@ mt7996_mcu_get_mmps_mode(enum ieee80211_smps_mode smps)
 int mt7996_mcu_set_fixed_rate_ctrl(struct mt7996_dev *dev,
 				   void *data, u16 version)
 {
+	struct uni_header hdr = {};
 	struct ra_fixed_rate *req;
-	struct uni_header hdr;
 	struct sk_buff *skb;
 	struct tlv *tlv;
 	int len;
@@ -3373,7 +3373,7 @@ int mt7996_mcu_set_hdr_trans(struct mt7996_dev *dev, bool hdr_trans)
 {
 	struct {
 		u8 __rsv[4];
-	} __packed hdr;
+	} __packed hdr = {};
 	struct hdr_trans_blacklist *req_blacklist;
 	struct hdr_trans_en *req_en;
 	struct sk_buff *skb;

---
base-commit: eb8352ee2d1e70f916fac02094dca2b435076fa4
change-id: 20250715-mt7996-fix-uninit-const-pointer-01e1dd03d444

Best regards,
--  
Nathan Chancellor <nathan@...nel.org>