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[213.8.172.158]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488d58bb830sm127720075e9.7.2026.04.10.23.24.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Apr 2026 23:24:43 -0700 (PDT) From: Michael Zaidman To: jikos@kernel.org, benjamin.tissoires@redhat.com Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, sebasjosue84@gmail.com, Michael Zaidman Subject: [PATCH v2] HID: ft260: validate i2c input report length Date: Sat, 11 Apr 2026 09:24:37 +0300 Message-Id: <20260411062437.279838-1-michael.zaidman@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add two checks to ft260_raw_event() to prevent out-of-bounds reads from malicious or malfunctioning devices: First, reject reports shorter than the 2-byte header (report ID + length fields). Without this, even accessing xfer->length on a 1-byte report is an OOB read. Second, validate xfer->length against the actual data capacity of the received HID report. Each I2C data report ID (0xD0 through 0xDE) defines a different report size in the HID descriptor, so the available payload varies per report. A corrupted length field could cause memcpy to read beyond the report buffer. Reported-by: Sebastián Josué Alba Vives Signed-off-by: Michael Zaidman --- Changes in v2: - Add minimum report size check before accessing header fields to prevent OOB read on truncated reports (size < 2) Tested on FT260 with I2C-attached EEPROM (24c02) behind PCA9548 mux switches. Verified reads of various sizes (1-4 bytes using report ID 0xD0, and larger reads using higher report IDs) with debug tracing enabled, confirming xfer->length is correctly validated against the HID report size for each report ID. --- drivers/hid/hid-ft260.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c index 333341e80b0e..70e2eedb465a 100644 --- a/drivers/hid/hid-ft260.c +++ b/drivers/hid/hid-ft260.c @@ -1068,10 +1068,22 @@ static int ft260_raw_event(struct hid_device *hdev, struct hid_report *report, struct ft260_device *dev = hid_get_drvdata(hdev); struct ft260_i2c_input_report *xfer = (void *)data; + if (size < offsetof(struct ft260_i2c_input_report, data)) { + hid_err(hdev, "short report %d\n", size); + return -1; + } + if (xfer->report >= FT260_I2C_REPORT_MIN && xfer->report <= FT260_I2C_REPORT_MAX) { - ft260_dbg("i2c resp: rep %#02x len %d\n", xfer->report, - xfer->length); + ft260_dbg("i2c resp: rep %#02x len %d size %d\n", + xfer->report, xfer->length, size); + + if (xfer->length > size - + offsetof(struct ft260_i2c_input_report, data)) { + hid_err(hdev, "report %#02x: length %d exceeds HID report size\n", + xfer->report, xfer->length); + return -1; + } if ((dev->read_buf == NULL) || (xfer->length > dev->read_len - dev->read_idx)) { -- 2.25.1