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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id c24sm28499040pgj.57.2022.01.05.10.02.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Jan 2022 10:02:16 -0800 (PST) From: Kees Cook To: Lars-Peter Clausen Cc: Kees Cook , Michael Hennerich , Cosmin Tanislav , Jonathan Cameron , linux-iio@vger.kernel.org, Linus Walleij , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2] iio: addac: Do not reference negative array offsets Date: Wed, 5 Jan 2022 10:02:14 -0800 Message-Id: <20220105180214.2435001-1-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2254; h=from:subject; bh=sGHoQxGNcT2Kv4+f7h+VZ51sTNIi0mtsXNE1v+t3ApI=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBh1d0lM+4aPs0jyUT1zIY3p2331EZ11B0G+kBU0nyj Jcsj1AWJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYdXdJQAKCRCJcvTf3G3AJvGfD/ 0Ut8I5/wxM912CDP+SrbegTwNbdz3eNsh2P4jKCPXaOmJ8sY8BBFtUAqEnWjGwWq2CVRKstBsYiAZl /+NwcXCNPt5VrLaEUI+GtZOGiTN8qml6bh0/LN+VF1iFGqTmXr8MgT0/dK///ubvK2gcVZfecWhoX8 7L3vHNHmSb3pwcbHyrMQMvoHa3jGjj8sjNr6v/F12SOfGFB7boVa87MVcNIDcng14m4bGQY0LamHlO ecKlMRMMBJSCDMFk0CzFWIWqg4yBT0ggv+n52uKlMBvCNHMoudn0gv3ld3EWuUSNV4kOHVJfLY+He+ vbiRN3Wy+AOIT5taUrYH50SqGp9Rk4Nx5Tz+HAHU+67CsBNmBLcRytkkujt7v2/9UZ/IQ3nW7vLvOf 2GlaGJ5eLCwCwKCnPnIyfSjyoeHgLeSbGRwzaQkjjU8uURk6eEP0oRgbUS0CUs1EIBPB7ODEI5AKW6 zs1E5JseyeKBsjVi8S6AwyYDoH6XWQrwqTqh/1p1FKbyRNIBKe7ykQjxfH/xTtx1H5GAaQU104tY3u eEDzC0AR6WV/sSRw8nIQWbHhb6tURMGErU6hqRKXFM0dY6x5Pcs5XgROqRe66RGmmzGpz6LWK3Kdn1 +pAtH455SfdNcYuFLILhyAWfNiRpYKAuKMV4kX0Uy5UozDVsUe4uyllFkLoA== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org Instead of aiming rx_buf at an invalid array-boundary-crossing location, just skip the first increment. Fixes this warning seen when building with -Warray-bounds: drivers/iio/addac/ad74413r.c: In function 'ad74413r_update_scan_mode': drivers/iio/addac/ad74413r.c:843:22: warning: array subscript -4 is below array bounds of 'u8[16]' { aka 'unsigned char[16]'} [-Warray-bounds] 843 | u8 *rx_buf = &st->adc_samples_buf.rx_buf[-1 * AD74413R_FRAME_SIZE]; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/iio/addac/ad74413r.c:84:20: note: while referencing 'rx_buf' 84 | u8 rx_buf[AD74413R_FRAME_SIZE * AD74413R_CHANNEL_MAX]; | ^~~~~~ Cc: Lars-Peter Clausen Cc: Michael Hennerich Cc: Cosmin Tanislav Cc: Jonathan Cameron Cc: linux-iio@vger.kernel.org Fixes: fea251b6a5db ("iio: addac: add AD74413R driver") Signed-off-by: Kees Cook --- v1: https://lore.kernel.org/lkml/20211215232321.2069314-1-keescook@chromium.org/ v2: - use "xfer" for checking "first through the loop" --- drivers/iio/addac/ad74413r.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/iio/addac/ad74413r.c b/drivers/iio/addac/ad74413r.c index 5271073bb74e..aba9a643a4ca 100644 --- a/drivers/iio/addac/ad74413r.c +++ b/drivers/iio/addac/ad74413r.c @@ -840,7 +840,7 @@ static int ad74413r_update_scan_mode(struct iio_dev *indio_dev, { struct ad74413r_state *st = iio_priv(indio_dev); struct spi_transfer *xfer = st->adc_samples_xfer; - u8 *rx_buf = &st->adc_samples_buf.rx_buf[-1 * AD74413R_FRAME_SIZE]; + u8 *rx_buf = st->adc_samples_buf.rx_buf; u8 *tx_buf = st->adc_samples_tx_buf; unsigned int channel; int ret = -EINVAL; @@ -894,9 +894,10 @@ static int ad74413r_update_scan_mode(struct iio_dev *indio_dev, spi_message_add_tail(xfer, &st->adc_samples_msg); - xfer++; tx_buf += AD74413R_FRAME_SIZE; - rx_buf += AD74413R_FRAME_SIZE; + if (xfer != st->adc_samples_xfer) + rx_buf += AD74413R_FRAME_SIZE; + xfer++; } xfer->rx_buf = rx_buf; -- 2.30.2