linux-kernel - [PATCH 5/6] ksmbd: improve exception handling and avoid redundant sanity check in loop

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Date:   Sun, 15 Jan 2023 18:32:08 +0800
From:   Dawei Li <set_pte_at@...look.com>
To:     linkinjeon@...nel.org, sfrench@...ba.org
Cc:     senozhatsky@...omium.org, tom@...pey.com, hyc.lee@...il.com,
        linux-cifs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 5/6] ksmbd: improve exception handling and avoid redundant sanity check in loop

1. Sanity check on validity of hook is supposed to be static,
   move it from looping.

2. If exception occurs after kvmalloc(), kvfree() is supposed
   to reclaim memory to avoid mem leak.

Signed-off-by: Dawei Li <set_pte_at@...look.com>
---
 fs/ksmbd/connection.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/ksmbd/connection.c b/fs/ksmbd/connection.c
index 36d1da273edd..b302de5db990 100644
--- a/fs/ksmbd/connection.c
+++ b/fs/ksmbd/connection.c
@@ -287,6 +287,12 @@ int ksmbd_conn_handler_loop(void *p)
 	mutex_init(&conn->srv_mutex);
 	__module_get(THIS_MODULE);
 
+	if (unlikely(!default_conn_ops.process_fn)) {
+		pr_err("No connection request callback\n");
+		module_put(THIS_MODULE);
+		return -EINVAL;
+	}
+
 	if (t->ops->prepare && t->ops->prepare(t))
 		goto out;
 
@@ -324,8 +330,10 @@ int ksmbd_conn_handler_loop(void *p)
 			break;
 
 		memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf));
-		if (!ksmbd_smb_request(conn))
+		if (!ksmbd_smb_request(conn)) {
+			pr_err("Invalid smb request\n");
 			break;
+		}
 
 		/*
 		 * We already read 4 bytes to find out PDU size, now
@@ -343,22 +351,18 @@ int ksmbd_conn_handler_loop(void *p)
 			continue;
 		}
 
-		if (!default_conn_ops.process_fn) {
-			pr_err("No connection request callback\n");
-			break;
-		}
-
 		if (default_conn_ops.process_fn(conn)) {
 			pr_err("Cannot handle request\n");
 			break;
 		}
 	}
 
+	kvfree(conn->request_buf);
+	conn->request_buf = NULL;
 out:
-	/* Wait till all reference dropped to the Server object*/
+	/* Wait till all reference dropped to the Server object */
 	wait_event(conn->r_count_q, atomic_read(&conn->r_count) == 0);
 
-
 	if (IS_ENABLED(CONFIG_UNICODE))
 		utf8_unload(conn->um);
 	unload_nls(conn->local_nls);
-- 
2.25.1