From 97839ca4b06ab27790700ad7da6be9a75fc0cc1d Mon Sep 17 00:00:00 2001 From: Chao Bi Date: Mon, 14 Apr 2014 11:19:53 +0800 Subject: [PATCH] usb: gadget: ffs: race between ffs_epfile_io() and ffs_func_eps_disable() ffs_epfile_io() is called from userspace, while ffs_func_eps_disable() might be called from USB disconnect interrupt, the two functions would run in parallel but they are not well protected, that epfile->ep would be removed by ffs_func_eps_disable() during ffs_epfile_io() is referring this pointer, then it leads to kernel PANIC. The scenario is as below: Thread 1 Thread 2 | | SyS_read dwc3_gadget_disconnect_interrupt | | ffs_epfile_read reset_config | | ffs_epfile_io ffs_func_eps_disable | | ----- usb_ep_disable(): epfile->ep->ep->desc = NULL | | usb_ep_align_maybe(): ----- it refers ep->desc->wMaxPacketSize ----- Signed-off-by: Chao Bi Signed-off-by: Felipe Balbi --- drivers/usb/gadget/f_fs.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c index 2e164dca08e8..1e12b3ee56fd 100644 --- a/drivers/usb/gadget/f_fs.c +++ b/drivers/usb/gadget/f_fs.c @@ -745,6 +745,12 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) */ struct usb_gadget *gadget = epfile->ffs->gadget; + spin_lock_irq(&epfile->ffs->eps_lock); + /* In the meantime, endpoint got disabled or changed. */ + if (epfile->ep != ep) { + spin_unlock_irq(&epfile->ffs->eps_lock); + return -ESHUTDOWN; + } /* * Controller may require buffer size to be aligned to * maxpacketsize of an out endpoint. @@ -752,6 +758,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) data_len = io_data->read ? usb_ep_align_maybe(gadget, ep->ep, io_data->len) : io_data->len; + spin_unlock_irq(&epfile->ffs->eps_lock); data = kmalloc(data_len, GFP_KERNEL); if (unlikely(!data))