linux-kernel - [PATCH 1/5] usb: f_fs: fix memory leak when ep changes during transfer

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Date:	Mon,  4 Jan 2016 22:41:37 +0100
From:	Michal Nazarewicz <mina86@...a86.com>
To:	Felipe Balbi <balbi@...com>, "Du, Changbin" <changbin.du@...el.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Robert Baldyga <r.baldyga@...sung.com>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Michal Nazarewicz <mina86@...a86.com>
Subject: [PATCH 1/5] usb: f_fs: fix memory leak when ep changes during transfer

In the ffs_epfile_io function, data buffer is allocated for non-halt
requests.  Later, after grabing a mutex, the function checks that
epfile->ep is still ep and if it’s not, it set ret to -ESHUTDOWN and
follow a path including spin_unlock_irq (just after ‘ret = -ESHUTDOWN’),
mutex_unlock (after if-else-if-else chain) and returns ret.  Noticeably,
this does not include freeing of the data buffer.

Fix by introducing a goto which moves control flow to the the end of the
function where spin_unlock_irq, mutex_unlock and kfree are all called.

Signed-off-by: Michal Nazarewicz <mina86@...a86.com>
---
 drivers/usb/gadget/function/f_fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index cf43e9e..d1a4a86 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -763,7 +763,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 	if (epfile->ep != ep) {
 		/* In the meantime, endpoint got disabled or changed. */
 		ret = -ESHUTDOWN;
-		spin_unlock_irq(&epfile->ffs->eps_lock);
+		goto error_lock;
 	} else if (halt) {
 		/* Halt */
 		if (likely(epfile->ep == ep) && !WARN_ON(!ep->ep))
-- 
2.6.0.rc2.230.g3dd15c0

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