fs: dlm: fix use after free in midcomms commit

In the Linux kernel, the following vulnerability has been resolved:

fs: dlm: fix use after free in midcomms commit

While working on processing dlm message in softirq context I experienced
the following KASAN use-after-free warning:

[ 151.760477] ==================================================================
[ 151.761803] BUG: KASAN: use-after-free in dlm_midcomms_commit_mhandle+0x19d/0x4b0
[ 151.763414] Read of size 4 at addr ffff88811a980c60 by task lock_torture/1347

[ 151.765284] CPU: 7 PID: 1347 Comm: lock_torture Not tainted 6.1.0-rc4+ #2828
[ 151.766778] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-3.module+el8.7.0+16134+e5908aa2 04/01/2014
[ 151.768726] Call Trace:
[ 151.769277] <TASK>
[ 151.769748] dump_stack_lvl+0x5b/0x86
[ 151.770556] print_report+0x180/0x4c8
[ 151.771378] ? kasan_complete_mode_report_info+0x7c/0x1e0
[ 151.772241] ? dlm_midcomms_commit_mhandle+0x19d/0x4b0
[ 151.773069] kasan_report+0x93/0x1a0
[ 151.773668] ? dlm_midcomms_commit_mhandle+0x19d/0x4b0
[ 151.774514] __asan_load4+0x7e/0xa0
[ 151.775089] dlm_midcomms_commit_mhandle+0x19d/0x4b0
[ 151.775890] ? create_message.isra.29.constprop.64+0x57/0xc0
[ 151.776770] send_common+0x19f/0x1b0
[ 151.777342] ? remove_from_waiters+0x60/0x60
[ 151.778017] ? lock_downgrade+0x410/0x410
[ 151.778648] ? __this_cpu_preempt_check+0x13/0x20
[ 151.779421] ? rcu_lockdep_current_cpu_online+0x88/0xc0
[ 151.780292] _convert_lock+0x46/0x150
[ 151.780893] convert_lock+0x7b/0xc0
[ 151.781459] dlm_lock+0x3ac/0x580
[ 151.781993] ? 0xffffffffc0540000
[ 151.782522] ? torture_stop+0x120/0x120 [dlm_locktorture]
[ 151.783379] ? dlm_scan_rsbs+0xa70/0xa70
[ 151.784003] ? preempt_count_sub+0xd6/0x130
[ 151.784661] ? is_module_address+0x47/0x70
[ 151.785309] ? torture_stop+0x120/0x120 [dlm_locktorture]
[ 151.786166] ? 0xffffffffc0540000
[ 151.786693] ? lockdep_init_map_type+0xc3/0x360
[ 151.787414] ? 0xffffffffc0540000
[ 151.787947] torture_dlm_lock_sync.isra.3+0xe9/0x150 [dlm_locktorture]
[ 151.789004] ? torture_stop+0x120/0x120 [dlm_locktorture]
[ 151.789858] ? 0xffffffffc0540000
[ 151.790392] ? lock_torture_cleanup+0x20/0x20 [dlm_locktorture]
[ 151.791347] ? delay_tsc+0x94/0xc0
[ 151.791898] torture_ex_iter+0xc3/0xea [dlm_locktorture]
[ 151.792735] ? torture_start+0x30/0x30 [dlm_locktorture]
[ 151.793606] lock_torture+0x177/0x270 [dlm_locktorture]
[ 151.794448] ? torture_dlm_lock_sync.isra.3+0x150/0x150 [dlm_locktorture]
[ 151.795539] ? lock_torture_stats+0x80/0x80 [dlm_locktorture]
[ 151.796476] ? do_raw_spin_lock+0x11e/0x1e0
[ 151.797152] ? mark_held_locks+0x34/0xb0
[ 151.797784] ? _raw_spin_unlock_irqrestore+0x30/0x70
[ 151.798581] ? __kthread_parkme+0x79/0x110
[ 151.799246] ? trace_preempt_on+0x2a/0xf0
[ 151.799902] ? __kthread_parkme+0x79/0x110
[ 151.800579] ? preempt_count_sub+0xd6/0x130
[ 151.801271] ? __kasan_check_read+0x11/0x20
[ 151.801963] ? __kthread_parkme+0xec/0x110
[ 151.802630] ? lock_torture_stats+0x80/0x80 [dlm_locktorture]
[ 151.803569] kthread+0x192/0x1d0
[ 151.804104] ? kthread_complete_and_exit+0x30/0x30
[ 151.804881] ret_from_fork+0x1f/0x30
[ 151.805480] </TASK>

[ 151.806111] Allocated by task 1347:
[ 151.806681] kasan_save_stack+0x26/0x50
[ 151.807308] kasan_set_track+0x25/0x30
[ 151.807920] kasan_save_alloc_info+0x1e/0x30
[ 151.808609] __kasan_slab_alloc+0x63/0x80
[ 151.809263] kmem_cache_alloc+0x1ad/0x830
[ 151.809916] dlm_allocate_mhandle+0x17/0x20
[ 151.810590] dlm_midcomms_get_mhandle+0x96/0x260
[ 151.811344] _create_message+0x95/0x180
[ 151.811994] create_message.isra.29.constprop.64+0x57/0xc0
[ 151.812880] send_common+0x129/0x1b0
[ 151.813467] _convert_lock+0x46/0x150
[ 151.814074] convert_lock+0x7b/0xc0
[ 151.814648] dlm_lock+0x3ac/0x580
[ 151.815199] torture_dlm_lock_sync.isra.3+0xe9/0x150 [dlm_locktorture]
[ 151.816258] torture_ex_iter+0xc3/0xea [dlm_locktorture]
[ 151.817129] lock_t
---truncated---