usb: mtu3: fix kernel panic at qmu transfer done irq handler

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: usb: mtu3: fix kernel panic at qmu transfer done irq handler When handle qmu transfer irq, it will unlock @mtu->lock before give back request, if another thread handle disconnect event at the same time, and try to disable ep, it may lock @mtu->lock and free qmu ring, then qmu irq hanlder may get a NULL gpd, avoid the KE by checking gpd's value before handling it. e.g. qmu done irq on cpu0 thread running on cpu1 qmu_done_tx() handle gpd [0] mtu3_requ_complete() mtu3_gadget_ep_disable() unlock @mtu->lock give back request lock @mtu->lock mtu3_ep_disable() mtu3_gpd_ring_free() unlock @mtu->lock lock @mtu->lock get next gpd [1] [1]: goto [0] to handle next gpd, and next gpd may be NULL.

References

• https://git.kernel.org/stable/c/26ca30516b2c49dd04c134cbdf122311c538df98
• https://git.kernel.org/stable/c/012936502a9cb7b0604e85bb961eb15e2bb40dd9
• https://git.kernel.org/stable/c/ee53a7a88027cea765c68f3b00a50b8f58d6f786
• https://git.kernel.org/stable/c/f26273428657ef4ca74740e578ae45a3be492f6f
• https://git.kernel.org/stable/c/b636aff94a67be46582d4321d11743f1a10cc2c1
• https://git.kernel.org/stable/c/3a7d4959560a2ee493ef222e3b63d359365f41ec
• https://git.kernel.org/stable/c/d28f4091ea7ec3510fd6a3c6d433234e7a2bef14