[PATCH 3.16 26/99] brcmfmac: fix interface sanity check

[Ben Hutchings]

3.16.84-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Johan Hovold <johan@xxxxxxxxxx>

commit 3428fbcd6e6c0850b1a8b2a12082b7b2aabb3da3 upstream.

Make sure to use the current alternate setting when verifying the
interface descriptors to avoid binding to an invalid interface.

Failing to do so could cause the driver to misbehave or trigger a WARN()
in usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: 71bb244ba2fd ("brcm80211: fmac: add USB support for bcm43235/6/8 chipsets")
Cc: Arend van Spriel <arend@xxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
[bwh: Backported to 3.16:
 - Altsetting lookup is done by the IFALTS() macro
 - Adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/net/wireless/brcm80211/brcmfmac/usb.c
+++ b/drivers/net/wireless/brcm80211/brcmfmac/usb.c
@@ -41,7 +41,7 @@
 
 #define CONFIGDESC(usb)         (&((usb)->actconfig)->desc)
 #define IFPTR(usb, idx)         ((usb)->actconfig->interface[(idx)])
-#define IFALTS(usb, idx)        (IFPTR((usb), (idx))->altsetting[0])
+#define IFALTS(usb, idx)        (*IFPTR((usb), (idx))->cur_altsetting)
 #define IFDESC(usb, idx)        IFALTS((usb), (idx)).desc
 #define IFEPDESC(usb, idx, ep)  (IFALTS((usb), (idx)).endpoint[(ep)]).desc