Bluetooth: btusb: mediatek: Fix kernel crash when releasing mtk iso interface

Summary

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btusb: mediatek: Fix kernel crash when releasing mtk iso interface When performing reset tests and encountering abnormal card drop issues that lead to a kernel crash, it is necessary to perform a null check before releasing resources to avoid attempting to release a null pointer. <4>[ 29.158070] Hardware name: Google Quigon sku196612/196613 board (DT) <4>[ 29.158076] Workqueue: hci0 hci_cmd_sync_work [bluetooth] <4>[ 29.158154] pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) <4>[ 29.158162] pc : klist_remove+0x90/0x158 <4>[ 29.158174] lr : klist_remove+0x88/0x158 <4>[ 29.158180] sp : ffffffc0846b3c00 <4>[ 29.158185] pmr_save: 000000e0 <4>[ 29.158188] x29: ffffffc0846b3c30 x28: ffffff80cd31f880 x27: ffffff80c1bdc058 <4>[ 29.158199] x26: dead000000000100 x25: ffffffdbdc624ea3 x24: ffffff80c1bdc4c0 <4>[ 29.158209] x23: ffffffdbdc62a3e6 x22: ffffff80c6c07000 x21: ffffffdbdc829290 <4>[ 29.158219] x20: 0000000000000000 x19: ffffff80cd3e0648 x18: 000000031ec97781 <4>[ 29.158229] x17: ffffff80c1bdc4a8 x16: ffffffdc10576548 x15: ffffff80c1180428 <4>[ 29.158238] x14: 0000000000000000 x13: 000000000000e380 x12: 0000000000000018 <4>[ 29.158248] x11: ffffff80c2a7fd10 x10: 0000000000000000 x9 : 0000000100000000 <4>[ 29.158257] x8 : 0000000000000000 x7 : 7f7f7f7f7f7f7f7f x6 : 2d7223ff6364626d <4>[ 29.158266] x5 : 0000008000000000 x4 : 0000000000000020 x3 : 2e7325006465636e <4>[ 29.158275] x2 : ffffffdc11afeff8 x1 : 0000000000000000 x0 : ffffffdc11be4d0c <4>[ 29.158285] Call trace: <4>[ 29.158290] klist_remove+0x90/0x158 <4>[ 29.158298] device_release_driver_internal+0x20c/0x268 <4>[ 29.158308] device_release_driver+0x1c/0x30 <4>[ 29.158316] usb_driver_release_interface+0x70/0x88 <4>[ 29.158325] btusb_mtk_release_iso_intf+0x68/0xd8 [btusb (HASH:e8b6 5)] <4>[ 29.158347] btusb_mtk_reset+0x5c/0x480 [btusb (HASH:e8b6 5)] <4>[ 29.158361] hci_cmd_sync_work+0x10c/0x188 [bluetooth (HASH:a4fa 6)] <4>[ 29.158430] process_scheduled_works+0x258/0x4e8 <4>[ 29.158441] worker_thread+0x300/0x428 <4>[ 29.158448] kthread+0x108/0x1d0 <4>[ 29.158455] ret_from_fork+0x10/0x20 <0>[ 29.158467] Code: 91343000 940139d1 f9400268 927ff914 (f9401297) <4>[ 29.158474] ---[ end trace 0000000000000000 ]--- <0>[ 29.167129] Kernel panic - not syncing: Oops: Fatal exception <2>[ 29.167144] SMP: stopping secondary CPUs <4>[ 29.167158] ------------[ cut here ]------------