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authorAndrzej Pietrasiewicz <andrzej.p@samsung.com>2014-01-20 11:33:50 +0400
committerFelipe Balbi <balbi@ti.com>2014-02-20 19:17:23 +0400
commitf0f42204d0cc04a63ac61fdaa3b6a269ea0dc08b (patch)
tree5e564e3f582d872a91433cc62dc1fa3ff8007cbd /drivers/usb
parent8679059e360543b7afecd228ada6566da9f304a4 (diff)
downloadlinux-f0f42204d0cc04a63ac61fdaa3b6a269ea0dc08b.tar.xz
usb: gadget: fix NULL pointer dereference
Fix possible NULL pointer dereference introduced in commit 219580e (usb: f_fs: check quirk to pad epout buf size when not aligned to maxpacketsize) In cases we do wait with: wait_event_interruptible(epfile->wait, (ep = epfile->ep)); for endpoint to be enabled, functionfs_bind() has not been called yet and epfile->ffs->gadget is still NULL and the automatic variable 'gadget' has been initialized with NULL at the point of its definition. Later on it is used as a parameter to: usb_ep_align_maybe(gadget, ep->ep, len) which in turn dereferences it. This patch fixes it by moving the actual assignment to the local 'gadget' variable after the potential waiting has completed. Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/gadget/f_fs.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 306a2b52125c..2b4334394076 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -585,7 +585,6 @@ static ssize_t ffs_epfile_io(struct file *file,
char __user *buf, size_t len, int read)
{
struct ffs_epfile *epfile = file->private_data;
- struct usb_gadget *gadget = epfile->ffs->gadget;
struct ffs_ep *ep;
char *data = NULL;
ssize_t ret, data_len;
@@ -622,6 +621,12 @@ static ssize_t ffs_epfile_io(struct file *file,
/* Allocate & copy */
if (!halt) {
/*
+ * if we _do_ wait above, the epfile->ffs->gadget might be NULL
+ * before the waiting completes, so do not assign to 'gadget' earlier
+ */
+ struct usb_gadget *gadget = epfile->ffs->gadget;
+
+ /*
* Controller may require buffer size to be aligned to
* maxpacketsize of an out endpoint.
*/