RDMA/hns: Fix NULL pointer problem in free_mr_init()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/hns: Fix NULL pointer problem in free_mr_init() Lock grab occurs in a concurrent scenario, resulting in stepping on a NULL pointer. It should be init mutex_init() first before use the lock. Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Call trace: __mutex_lock.constprop.0+0xd0/0x5c0 __mutex_lock_slowpath+0x1c/0x2c mutex_lock+0x44/0x50 free_mr_send_cmd_to_hw+0x7c/0x1c0 [hns_roce_hw_v2] hns_roce_v2_dereg_mr+0x30/0x40 [hns_roce_hw_v2] hns_roce_dereg_mr+0x4c/0x130 [hns_roce_hw_v2] ib_dereg_mr_user+0x54/0x124 uverbs_free_mr+0x24/0x30 destroy_hw_idr_uobject+0x38/0x74 uverbs_destroy_uobject+0x48/0x1c4 uobj_destroy+0x74/0xcc ib_uverbs_cmd_verbs+0x368/0xbb0 ib_uverbs_ioctl+0xec/0x1a4 __arm64_sys_ioctl+0xb4/0x100 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0x58/0x190 do_el0_svc+0x30/0x90 el0_svc+0x2c/0xb4 el0t_64_sync_handler+0x1a4/0x1b0 el0t_64_sync+0x19c/0x1a0

References

• https://git.kernel.org/stable/c/0e23e85d86b78e734dd6654f1b69fbaeb5534c81
• https://git.kernel.org/stable/c/12bcaf87d8b66d8cd812479c8a6349dcb245375c