smb: client: fix NULL ptr deref in crypto_aead_setkey()

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

smb: client: fix NULL ptr deref in crypto_aead_setkey()

Neither SMB3.0 or SMB3.02 supports encryption negotiate context, so
when SMB2_GLOBAL_CAP_ENCRYPTION flag is set in the negotiate response,
the client uses AES-128-CCM as the default cipher. See MS-SMB2
3.3.5.4.

Commit b0abcd65ec54 ("smb: client: fix UAF in async decryption") added
a @server->cipher_type check to conditionally call
smb3_crypto_aead_allocate(), but that check would always be false as
@server->cipher_type is unset for SMB3.02.

Fix the following KASAN splat by setting @server->cipher_type for
SMB3.02 as well.

mount.cifs //srv/share /mnt -o vers=3.02,seal,...

BUG: KASAN: null-ptr-deref in crypto_aead_setkey+0x2c/0x130
Read of size 8 at addr 0000000000000020 by task mount.cifs/1095
CPU: 1 UID: 0 PID: 1095 Comm: mount.cifs Not tainted 6.12.0 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-3.fc41
04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x5d/0x80
? crypto_aead_setkey+0x2c/0x130
kasan_report+0xda/0x110
? crypto_aead_setkey+0x2c/0x130
crypto_aead_setkey+0x2c/0x130
crypt_message+0x258/0xec0 [cifs]
? __asan_memset+0x23/0x50
? __pfx_crypt_message+0x10/0x10 [cifs]
? mark_lock+0xb0/0x6a0
? hlock_class+0x32/0xb0
? mark_lock+0xb0/0x6a0
smb3_init_transform_rq+0x352/0x3f0 [cifs]
? lock_acquire.part.0+0xf4/0x2a0
smb_send_rqst+0x144/0x230 [cifs]
? __pfx_smb_send_rqst+0x10/0x10 [cifs]
? hlock_class+0x32/0xb0
? smb2_setup_request+0x225/0x3a0 [cifs]
? __pfx_cifs_compound_last_callback+0x10/0x10 [cifs]
compound_send_recv+0x59b/0x1140 [cifs]
? __pfx_compound_send_recv+0x10/0x10 [cifs]
? __create_object+0x5e/0x90
? hlock_class+0x32/0xb0
? do_raw_spin_unlock+0x9a/0xf0
cifs_send_recv+0x23/0x30 [cifs]
SMB2_tcon+0x3ec/0xb30 [cifs]
? __pfx_SMB2_tcon+0x10/0x10 [cifs]
? lock_acquire.part.0+0xf4/0x2a0
? __pfx_lock_release+0x10/0x10
? do_raw_spin_trylock+0xc6/0x120
? lock_acquire+0x3f/0x90
? _get_xid+0x16/0xd0 [cifs]
? __pfx_SMB2_tcon+0x10/0x10 [cifs]
? cifs_get_smb_ses+0xcdd/0x10a0 [cifs]
cifs_get_smb_ses+0xcdd/0x10a0 [cifs]
? __pfx_cifs_get_smb_ses+0x10/0x10 [cifs]
? cifs_get_tcp_session+0xaa0/0xca0 [cifs]
cifs_mount_get_session+0x8a/0x210 [cifs]
dfs_mount_share+0x1b0/0x11d0 [cifs]
? __pfx___lock_acquire+0x10/0x10
? __pfx_dfs_mount_share+0x10/0x10 [cifs]
? lock_acquire.part.0+0xf4/0x2a0
? find_held_lock+0x8a/0xa0
? hlock_class+0x32/0xb0
? lock_release+0x203/0x5d0
cifs_mount+0xb3/0x3d0 [cifs]
? do_raw_spin_trylock+0xc6/0x120
? __pfx_cifs_mount+0x10/0x10 [cifs]
? lock_acquire+0x3f/0x90
? find_nls+0x16/0xa0
? smb3_update_mnt_flags+0x372/0x3b0 [cifs]
cifs_smb3_do_mount+0x1e2/0xc80 [cifs]
? __pfx_vfs_parse_fs_string+0x10/0x10
? __pfx_cifs_smb3_do_mount+0x10/0x10 [cifs]
smb3_get_tree+0x1bf/0x330 [cifs]
vfs_get_tree+0x4a/0x160
path_mount+0x3c1/0xfb0
? kasan_quarantine_put+0xc7/0x1d0
? __pfx_path_mount+0x10/0x10
? kmem_cache_free+0x118/0x3e0
? user_path_at+0x74/0xa0
__x64_sys_mount+0x1a6/0x1e0
? __pfx___x64_sys_mount+0x10/0x10
? mark_held_locks+0x1a/0x90
do_syscall_64+0xbb/0x1d0
entry_SYSCALL_64_after_hwframe+0x77/0x7f