[PATCH 4.9 30/32] usb: musb: trace: fix NULL pointer dereference in musb_g_tx()

From: Greg Kroah-Hartman
Date: Tue May 08 2018 - 04:19:05 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Bin Liu <b-liu@xxxxxx>

commit 9aea9b6cc78d2b99b23d84fb2e0bc6e464c6569e upstream.

The usb_request pointer could be NULL in musb_g_tx(), where the
tracepoint call would trigger the NULL pointer dereference failure when
parsing the members of the usb_request pointer.

Move the tracepoint call to where the usb_request pointer is already
checked to solve the issue.

Fixes: fc78003e5345 ("usb: musb: gadget: add usb-request tracepoints")
Cc: stable@xxxxxxxxxxxxxxx # v4.8+
Signed-off-by: Bin Liu <b-liu@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/usb/musb/musb_gadget.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -442,7 +442,6 @@ void musb_g_tx(struct musb *musb, u8 epn
req = next_request(musb_ep);
request = &req->request;

- trace_musb_req_tx(req);
csr = musb_readw(epio, MUSB_TXCSR);
musb_dbg(musb, "<== %s, txcsr %04x", musb_ep->end_point.name, csr);

@@ -481,6 +480,8 @@ void musb_g_tx(struct musb *musb, u8 epn
u8 is_dma = 0;
bool short_packet = false;

+ trace_musb_req_tx(req);
+
if (dma && (csr & MUSB_TXCSR_DMAENAB)) {
is_dma = 1;
csr |= MUSB_TXCSR_P_WZC_BITS;