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 b0abcd6 ("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

Cc: Tom Talpey <[email protected]>
Reported-by: Jianhong Yin <[email protected]>
Cc: [email protected] # v6.12
Fixes: b0abcd6 ("smb: client: fix UAF in async decryption")
Signed-off-by: Paulo Alcantara (Red Hat) <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: Paulo Alcantara

fs/smb/client/smb2pdu.c

@@ -1231,7 +1231,9 @@ SMB2_negotiate(const unsigned int xid,
 	 * SMB3.0 supports only 1 cipher and doesn't have a encryption neg context
 	 * Set the cipher type manually.
 	 */
-	if (server->dialect == SMB30_PROT_ID && (server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION))
+	if ((server->dialect == SMB30_PROT_ID ||
+	     server->dialect == SMB302_PROT_ID) &&
+	    (server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION))
 		server->cipher_type = SMB2_ENCRYPTION_AES128_CCM;
 
 	security_blob = smb2_get_data_area_len(&blob_offset, &blob_length,