diff mbox series

[v4,2/2] usb: gadget: f_fs: change ep->ep safe in ffs_epfile_io()

Message ID 1654311295-9700-3-git-send-email-quic_linyyuan@quicinc.com (mailing list archive)
State Superseded
Commit 0698f0209d8032e8869525aeb68f65ee7fde12ad
Headers show
Series usb: f_fs: safe operation in ffs_epfile_io() | expand

Commit Message

Linyu Yuan June 4, 2022, 2:54 a.m. UTC 
In ffs_epfile_io(), when read/write data in blocking mode, it will wait
the completion in interruptible mode, if task receive a signal, it will
terminate the wait, at same time, if function unbind occurs,
ffs_func_unbind() will kfree all eps, ffs_epfile_io() still try to
dequeue request by dereferencing ep which may become invalid.

Fix it by add ep spinlock and will not dereference ep if it is not valid.

Cc: <stable@vger.kernel.org> # 5.15
Reported-by: Michael Wu <michael@allwinnertech.com>
Tested-by: Michael Wu <michael@allwinnertech.com>
Reviewed-by: John Keeping <john@metanate.com>
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
---
v2: add Reviewed-by from John keeping
v3: add Reported-by from Michael Wu
v4: add Tested-by from Michael Wu
    cc stable kernel

 drivers/usb/gadget/function/f_fs.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff mbox series

Patch

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 3958c60..b0c046a 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -1077,6 +1077,11 @@  static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 		spin_unlock_irq(&epfile->ffs->eps_lock);
 
 		if (wait_for_completion_interruptible(&io_data->done)) {
+			spin_lock_irq(&epfile->ffs->eps_lock);
+			if (epfile->ep != ep) {
+				ret = -ESHUTDOWN;
+				goto error_lock;
+			}
 			/*
 			 * To avoid race condition with ffs_epfile_io_complete,
 			 * dequeue the request first then check
@@ -1084,6 +1089,7 @@  static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 			 * condition with req->complete callback.
 			 */
 			usb_ep_dequeue(ep->ep, req);
+			spin_unlock_irq(&epfile->ffs->eps_lock);
 			wait_for_completion(&io_data->done);
 			interrupted = io_data->status < 0;
 		}