From 4833a94eb383f5b22775077ff92ddaae90440921 Mon Sep 17 00:00:00 2001 From: Fei Yang Date: Wed, 12 Jun 2019 15:13:26 -0700 Subject: usb: gadget: f_fs: data_len used before properly set 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 Cc: stable Signed-off-by: Felipe Balbi --- drivers/usb/gadget/function/f_fs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/usb/gadget') diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 47be961f1bf3..c7ed90084d1a 100644 --- 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 *file, struct ffs_io_data *io_data) * 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 *file, struct ffs_io_data *io_data) */ 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); -- cgit v1.2.3