ksmbd: return invalid parameter error response if smb2 request is invalid

If smb2 request from client is invalid, The following kernel oops could
happen. The patch e2b76ab8: "ksmbd: add support for read compound"
leads this issue. When request is invalid, It doesn't set anything in
the response buffer. This patch add missing set invalid parameter error
response.

[  673.085542] ksmbd: cli req too short, len 184 not 142. cmd:5 mid:109
[  673.085580] BUG: kernel NULL pointer dereference, address: 0000000000000000
[  673.085591] #PF: supervisor read access in kernel mode
[  673.085600] #PF: error_code(0x0000) - not-present page
[  673.085608] PGD 0 P4D 0
[  673.085620] Oops: 0000 [#1] PREEMPT SMP NOPTI
[  673.085631] CPU: 3 PID: 1039 Comm: kworker/3:0 Not tainted 6.6.0-rc2-tmt #16
[  673.085643] Hardware name: AZW U59/U59, BIOS JTKT001 05/05/2022
[  673.085651] Workqueue: ksmbd-io handle_ksmbd_work [ksmbd]
[  673.085719] RIP: 0010:ksmbd_conn_write+0x68/0xc0 [ksmbd]
[  673.085808] RAX: 0000000000000000 RBX: ffff88811ade4f00 RCX: 0000000000000000
[  673.085817] RDX: 0000000000000000 RSI: ffff88810c2a9780 RDI: ffff88810c2a9ac0
[  673.085826] RBP: ffffc900005e3e00 R08: 0000000000000000 R09: 0000000000000000
[  673.085834] R10: ffffffffa3168160 R11: 63203a64626d736b R12: ffff8881057c8800
[  673.085842] R13: ffff8881057c8820 R14: ffff8882781b2380 R15: ffff8881057c8800
[  673.085852] FS:  0000000000000000(0000) GS:ffff888278180000(0000) knlGS:0000000000000000
[  673.085864] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  673.085872] CR2: 0000000000000000 CR3: 000000015b63c000 CR4: 0000000000350ee0
[  673.085883] Call Trace:
[  673.085890]  <TASK>
[  673.085900]  ? show_regs+0x6a/0x80
[  673.085916]  ? __die+0x25/0x70
[  673.085926]  ? page_fault_oops+0x154/0x4b0
[  673.085938]  ? tick_nohz_tick_stopped+0x18/0x50
[  673.085954]  ? __irq_work_queue_local+0xba/0x140
[  673.085967]  ? do_user_addr_fault+0x30f/0x6c0
[  673.085979]  ? exc_page_fault+0x79/0x180
[  673.085992]  ? asm_exc_page_fault+0x27/0x30
[  673.086009]  ? ksmbd_conn_write+0x68/0xc0 [ksmbd]
[  673.086067]  ? ksmbd_conn_write+0x46/0xc0 [ksmbd]
[  673.086123]  handle_ksmbd_work+0x28d/0x4b0 [ksmbd]
[  673.086177]  process_one_work+0x178/0x350
[  673.086193]  ? __pfx_worker_thread+0x10/0x10
[  673.086202]  worker_thread+0x2f3/0x420
[  673.086210]  ? _raw_spin_unlock_irqrestore+0x27/0x50
[  673.086222]  ? __pfx_worker_thread+0x10/0x10
[  673.086230]  kthread+0x103/0x140
[  673.086242]  ? __pfx_kthread+0x10/0x10
[  673.086253]  ret_from_fork+0x39/0x60
[  673.086263]  ? __pfx_kthread+0x10/0x10
[  673.086274]  ret_from_fork_asm+0x1b/0x30

Fixes: e2b76ab8 ("ksmbd: add support for read compound")
Reported-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/server.c

@@ -115,8 +115,10 @@ static int __process_request(struct ksmbd_work *work, struct ksmbd_conn *conn,
 	if (check_conn_state(work))
 		return SERVER_HANDLER_CONTINUE;
 
-	if (ksmbd_verify_smb_message(work))
+	if (ksmbd_verify_smb_message(work)) {
+		conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
 		return SERVER_HANDLER_ABORT;
+	}
 
 	command = conn->ops->get_cmd_val(work);
 	*cmd = command;

fs/smb/server/smb2misc.c

@@ -440,10 +440,8 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
 
 validate_credit:
 	if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
-	    smb2_validate_credit_charge(work->conn, hdr)) {
-		work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
+	    smb2_validate_credit_charge(work->conn, hdr))
 		return 1;
-	}
 
 	return 0;
 }