From: Fei Yang <fei.yang@xxxxxxxxx>
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@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/f_fs.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 47be961..c7ed900 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);
--
2.7.4
