xhci: fix list access before init

If for whatever reason we fall into fail path in xhci_mem_init()
before bw table gets initialized we may access the uninitialized lists
in xhci_mem_cleanup().

Check for bw table before traversing lists in cleanup routine.

This patch should be backported to kernels as old as 3.2, that contain
the commit 839c817ce67178ca3c7c7ad534c571bba1e69ebe "xhci: Store
information about roothubs and TTs."

Reported-by: Sergey Dyasly <dserrg@gmail.com>
Tested-by: Sergey Dyasly <dserrg@gmail.com>
Signed-off-by: Vladimir Murzin <murzin.v@gmail.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index bda2c51a7c74..fbf75e57628b 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1827,6 +1827,9 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
         }
         spin_unlock_irqrestore(&xhci->lock, flags);
 
+        if (!xhci->rh_bw)
+                goto no_bw;
+
         num_ports = HCS_MAX_PORTS(xhci->hcs_params1);
         for (i = 0; i < num_ports; i++) {
                 struct xhci_interval_bw_table *bwt = &xhci->rh_bw[i].bw_table;
@@ -1845,6 +1848,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
                 }
         }
 
+no_bw:
         xhci->num_usb2_ports = 0;
         xhci->num_usb3_ports = 0;
         xhci->num_active_eps = 0;