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[93.34.92.187]) by smtp.googlemail.com with ESMTPSA id ffacd0b85a97d-48e254f0bc2sm6226569f8f.1.2026.10.21.09.09.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Oct 2026 09:09:34 -0700 (PDT) From: Christian Marangi To: Stefan Roese , Andi Shyti , Matthias Brugger , AngeloGioacchino Del Regno , Wolfram Sang , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Cc: Christian Marangi Subject: [PATCH] i2c: mt7621: fix copying uninitialized kernel stack with reduced page_len Date: Wed, 21 Oct 2026 18:09:24 +0200 Message-ID: <20261021160925.286424-1-ansuelsmth@gmail.com> X-Mailer: git-send-email 2.55.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When a page_len is less than 5 bytes in mtk_i2c_xfer, uninitialized kernel stack data is copied and written to REG_SM0D1_REG. Equally on the read part, an unnecessary read is done. Guard these extra copy/write and read for the page_len to fix leaking uninitialized stack memory. Fixes: d04913ec5f89 ("i2c: mt7621: Add MediaTek MT7621/7628/7688 I2C driver") Signed-off-by: Christian Marangi --- drivers/i2c/busses/i2c-mt7621.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-mt7621.c b/drivers/i2c/busses/i2c-mt7621.c index 19dde7c4069e..b4d2f9c5514d 100644 --- a/drivers/i2c/busses/i2c-mt7621.c +++ b/drivers/i2c/busses/i2c-mt7621.c @@ -96,7 +96,8 @@ static void mtk_i2c_reset(struct mtk_i2c *i2c) * configure open-drain mode, this bit needs to be cleared. */ reg = ((i2c->clk_div << 16) & SM0CTL0_CLK_DIV_MASK) | SM0CTL0_EN; - if (i2c->have_scl_stretch) + /* Set SCL_STRETCH only for Mediatek SoC */ + if (device_is_compatible(i2c->dev, "mediatek,mt7621-i2c")) reg |= SM0CTL0_SCL_STRETCH; iowrite32(reg, i2c->base + REG_SM0CTL0_REG); @@ -302,9 +303,8 @@ static int mtk_i2c_probe(struct platform_device *pdev) return -EINVAL; } - /* Set SCL_STRETCH only for Mediatek SoC */ if (device_is_compatible(i2c->dev, "mediatek,mt7621-i2c")) - i2c->have_scl_stretch = true; + i2c->have_scl_stretch adap = &i2c->adap; adap->owner = THIS_MODULE; -- 2.55.0