This is a note to let you know that I've just added the patch titled HID: cp2112: prevent a buffer overflow in cp2112_xfer() to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: hid-cp2112-prevent-a-buffer-overflow-in-cp2112_xfer.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit c226e2234e65c900f27b8fbe7320caed498dc333 Author: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> Date: Wed Jun 8 05:26:09 2022 -0700 HID: cp2112: prevent a buffer overflow in cp2112_xfer() [ Upstream commit 381583845d19cb4bd21c8193449385f3fefa9caf ] Smatch warnings: drivers/hid/hid-cp2112.c:793 cp2112_xfer() error: __memcpy() 'data->block[1]' too small (33 vs 255) drivers/hid/hid-cp2112.c:793 cp2112_xfer() error: __memcpy() 'buf' too small (64 vs 255) The 'read_length' variable is provided by 'data->block[0]' which comes from user and it(read_length) can take a value between 0-255. Add an upper bound to 'read_length' variable to prevent a buffer overflow in memcpy(). Fixes: 542134c0375b ("HID: cp2112: Fix I2C_BLOCK_DATA transactions") Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> Signed-off-by: Jiri Kosina <jkosina@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c index 6f65f5257236..637a7ce281c6 100644 --- a/drivers/hid/hid-cp2112.c +++ b/drivers/hid/hid-cp2112.c @@ -794,6 +794,11 @@ static int cp2112_xfer(struct i2c_adapter *adap, u16 addr, data->word = le16_to_cpup((__le16 *)buf); break; case I2C_SMBUS_I2C_BLOCK_DATA: + if (read_length > I2C_SMBUS_BLOCK_MAX) { + ret = -EINVAL; + goto power_normal; + } + memcpy(data->block + 1, buf, read_length); break; case I2C_SMBUS_BLOCK_DATA: