cifs: Fix warning and UAF when destroy the MR list

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

cifs: Fix warning and UAF when destroy the MR list

If the MR allocate failed, the MR recovery work not initialized

and list not cleared. Then will be warning and UAF when release

the MR:

WARNING: CPU: 4 PID: 824 at kernel/workqueue.c:3066 __flush_work.isra.0+0xf7/0x110

CPU: 4 PID: 824 Comm: mount.cifs Not tainted 6.1.0-rc5+ #82

RIP: 0010:__flush_work.isra.0+0xf7/0x110

Call Trace:

<TASK>

__cancel_work_timer+0x2ba/0x2e0

smbd_destroy+0x4e1/0x990

_smbd_get_connection+0x1cbd/0x2110

smbd_get_connection+0x21/0x40

cifs_get_tcp_session+0x8ef/0xda0

mount_get_conns+0x60/0x750

cifs_mount+0x103/0xd00

cifs_smb3_do_mount+0x1dd/0xcb0

smb3_get_tree+0x1d5/0x300

vfs_get_tree+0x41/0xf0

path_mount+0x9b3/0xdd0

__x64_sys_mount+0x190/0x1d0

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x46/0xb0

BUG: KASAN: use-after-free in smbd_destroy+0x4fc/0x990

Read of size 8 at addr ffff88810b156a08 by task mount.cifs/824

CPU: 4 PID: 824 Comm: mount.cifs Tainted: G W 6.1.0-rc5+ #82

Call Trace:

dump_stack_lvl+0x34/0x44

print_report+0x171/0x472

kasan_report+0xad/0x130

smbd_destroy+0x4fc/0x990

_smbd_get_connection+0x1cbd/0x2110

smbd_get_connection+0x21/0x40

cifs_get_tcp_session+0x8ef/0xda0

mount_get_conns+0x60/0x750

cifs_mount+0x103/0xd00

cifs_smb3_do_mount+0x1dd/0xcb0

smb3_get_tree+0x1d5/0x300

vfs_get_tree+0x41/0xf0

path_mount+0x9b3/0xdd0

__x64_sys_mount+0x190/0x1d0

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x46/0xb0

Allocated by task 824:

kasan_save_stack+0x1e/0x40

kasan_set_track+0x21/0x30

__kasan_kmalloc+0x7a/0x90

_smbd_get_connection+0x1b6f/0x2110

smbd_get_connection+0x21/0x40

cifs_get_tcp_session+0x8ef/0xda0

mount_get_conns+0x60/0x750

cifs_mount+0x103/0xd00

cifs_smb3_do_mount+0x1dd/0xcb0

smb3_get_tree+0x1d5/0x300

vfs_get_tree+0x41/0xf0

path_mount+0x9b3/0xdd0

__x64_sys_mount+0x190/0x1d0

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x46/0xb0

Freed by task 824:

kasan_save_stack+0x1e/0x40

kasan_set_track+0x21/0x30

kasan_save_free_info+0x2a/0x40

____kasan_slab_free+0x143/0x1b0

__kmem_cache_free+0xc8/0x330

_smbd_get_connection+0x1c6a/0x2110

smbd_get_connection+0x21/0x40

cifs_get_tcp_session+0x8ef/0xda0

mount_get_conns+0x60/0x750

cifs_mount+0x103/0xd00

cifs_smb3_do_mount+0x1dd/0xcb0

smb3_get_tree+0x1d5/0x300

vfs_get_tree+0x41/0xf0

path_mount+0x9b3/0xdd0

__x64_sys_mount+0x190/0x1d0

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x46/0xb0

Let's initialize the MR recovery work before MR allocate to prevent

the warning, remove the MRs from the list to prevent the UAF.