From: Johan Hovold <johan@xxxxxxxxxx> commit 020a1f453449294926ca548d8d5ca970926e8dfd upstream. Stack-allocated buffers cannot be used for DMA (on all architectures). Replace the HP-channel macro with a helper function that allocates a dedicated transfer buffer so that it can continue to be used with arguments from the stack. Note that the buffer is cleared on allocation as usblp_ctrl_msg() returns success also on short transfers (the buffer is only used for debugging). Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210104145302.2087-1-johan@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/class/usblp.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) --- a/drivers/usb/class/usblp.c +++ b/drivers/usb/class/usblp.c @@ -274,8 +274,25 @@ static int usblp_ctrl_msg(struct usblp * #define usblp_reset(usblp)\ usblp_ctrl_msg(usblp, USBLP_REQ_RESET, USB_TYPE_CLASS, USB_DIR_OUT, USB_RECIP_OTHER, 0, NULL, 0) -#define usblp_hp_channel_change_request(usblp, channel, buffer) \ - usblp_ctrl_msg(usblp, USBLP_REQ_HP_CHANNEL_CHANGE_REQUEST, USB_TYPE_VENDOR, USB_DIR_IN, USB_RECIP_INTERFACE, channel, buffer, 1) +static int usblp_hp_channel_change_request(struct usblp *usblp, int channel, u8 *new_channel) +{ + u8 *buf; + int ret; + + buf = kzalloc(1, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + ret = usblp_ctrl_msg(usblp, USBLP_REQ_HP_CHANNEL_CHANGE_REQUEST, + USB_TYPE_VENDOR, USB_DIR_IN, USB_RECIP_INTERFACE, + channel, buf, 1); + if (ret == 0) + *new_channel = buf[0]; + + kfree(buf); + + return ret; +} /* * See the description for usblp_select_alts() below for the usage
