From: Fei Yang fei.yang@intel.com
commit 4833a94eb383f5b22775077ff92ddaae90440921 upstream.
The following line of code in function ffs_epfile_io is trying to set flag io_data->use_sg in case buffer required is larger than one page.
io_data->use_sg = gadget->sg_supported && data_len > PAGE_SIZE;
However at this point of time the variable data_len has not been set to the proper buffer size yet. The consequence is that io_data->use_sg is always set regardless what buffer size really is, because the condition (data_len > PAGE_SIZE) is effectively an unsigned comparison between -EINVAL and PAGE_SIZE which would always result in TRUE.
Fixes: 772a7a724f69 ("usb: gadget: f_fs: Allow scatter-gather buffers") Signed-off-by: Fei Yang fei.yang@intel.com Cc: stable stable@vger.kernel.org Signed-off-by: Felipe Balbi felipe.balbi@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/gadget/function/f_fs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -997,7 +997,6 @@ static ssize_t ffs_epfile_io(struct file * earlier */ gadget = epfile->ffs->gadget; - io_data->use_sg = gadget->sg_supported && data_len > PAGE_SIZE;
spin_lock_irq(&epfile->ffs->eps_lock); /* In the meantime, endpoint got disabled or changed. */ @@ -1012,6 +1011,8 @@ static ssize_t ffs_epfile_io(struct file */ if (io_data->read) data_len = usb_ep_align_maybe(gadget, ep->ep, data_len); + + io_data->use_sg = gadget->sg_supported && data_len > PAGE_SIZE; spin_unlock_irq(&epfile->ffs->eps_lock);
data = ffs_alloc_buffer(io_data, data_len);