1 files changed, 31 insertions, 28 deletions

diff --git a/fs/ksmbd/smb_common.c b/fs/ksmbd/smb_common.c
index 40f4fafa2e11..707490ab1f4c 100644
--- a/fs/ksmbd/smb_common.c
+++ b/fs/ksmbd/smb_common.c
@@ -21,7 +21,6 @@ static const char basechars[43] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_-!@#$%";
 #define MAGIC_CHAR '~'
 #define PERIOD '.'
 #define mangle(V) ((char)(basechars[(V) % MANGLE_BASE]))
-#define KSMBD_MIN_SUPPORTED_HEADER_SIZE	(sizeof(struct smb2_hdr))
 
 struct smb_protocol {
 	int		index;
@@ -89,7 +88,7 @@ unsigned int ksmbd_server_side_copy_max_total_size(void)
 
 inline int ksmbd_min_protocol(void)
 {
-	return SMB2_PROT;
+	return SMB21_PROT;
 }
 
 inline int ksmbd_max_protocol(void)
@@ -155,20 +154,7 @@ int ksmbd_verify_smb_message(struct ksmbd_work *work)
  */
 bool ksmbd_smb_request(struct ksmbd_conn *conn)
 {
-	int type = *(char *)conn->request_buf;
-
-	switch (type) {
-	case RFC1002_SESSION_MESSAGE:
-		/* Regular SMB request */
-		return true;
-	case RFC1002_SESSION_KEEP_ALIVE:
-		ksmbd_debug(SMB, "RFC 1002 session keep alive\n");
-		break;
-	default:
-		ksmbd_debug(SMB, "RFC 1002 unknown request type 0x%x\n", type);
-	}
-
-	return false;
+	return conn->request_buf[0] == 0;
 }
 
 static bool supported_protocol(int idx)
@@ -182,10 +168,12 @@ static bool supported_protocol(int idx)
 		idx <= server_conf.max_protocol);
 }
 
-static char *next_dialect(char *dialect, int *next_off)
+static char *next_dialect(char *dialect, int *next_off, int bcount)
 {
 	dialect = dialect + *next_off;
-	*next_off = strlen(dialect);
+	*next_off = strnlen(dialect, bcount);
+	if (dialect[*next_off] != '\0')
+		return NULL;
 	return dialect;
 }
 
@@ -200,7 +188,9 @@ static int ksmbd_lookup_dialect_by_name(char *cli_dialects, __le16 byte_count)
 		dialect = cli_dialects;
 		bcount = le16_to_cpu(byte_count);
 		do {
-			dialect = next_dialect(dialect, &next);
+			dialect = next_dialect(dialect, &next, bcount);
+			if (!dialect)
+				break;
 			ksmbd_debug(SMB, "client requested dialect %s\n",
 				    dialect);
 			if (!strcmp(dialect, smb1_protos[i].name)) {
@@ -248,13 +238,22 @@ int ksmbd_lookup_dialect_by_id(__le16 *cli_dialects, __le16 dialects_count)
 
 static int ksmbd_negotiate_smb_dialect(void *buf)
 {
-	__le32 proto;
+	int smb_buf_length = get_rfc1002_len(buf);
+	__le32 proto = ((struct smb2_hdr *)buf)->ProtocolId;
 
-	proto = ((struct smb2_hdr *)buf)->ProtocolId;
 	if (proto == SMB2_PROTO_NUMBER) {
 		struct smb2_negotiate_req *req;
+		int smb2_neg_size =
+			offsetof(struct smb2_negotiate_req, Dialects) - 4;
 
 		req = (struct smb2_negotiate_req *)buf;
+		if (smb2_neg_size > smb_buf_length)
+			goto err_out;
+
+		if (smb2_neg_size + le16_to_cpu(req->DialectCount) * sizeof(__le16) >
+		    smb_buf_length)
+			goto err_out;
+
 		return ksmbd_lookup_dialect_by_id(req->Dialects,
 						  req->DialectCount);
 	}
@@ -264,10 +263,19 @@ static int ksmbd_negotiate_smb_dialect(void *buf)
 		struct smb_negotiate_req *req;
 
 		req = (struct smb_negotiate_req *)buf;
+		if (le16_to_cpu(req->ByteCount) < 2)
+			goto err_out;
+
+		if (offsetof(struct smb_negotiate_req, DialectsArray) - 4 +
+			le16_to_cpu(req->ByteCount) > smb_buf_length) {
+			goto err_out;
+		}
+
 		return ksmbd_lookup_dialect_by_name(req->DialectsArray,
 						    req->ByteCount);
 	}
 
+err_out:
 	return BAD_PROT_ID;
 }
 
@@ -285,11 +293,6 @@ int ksmbd_init_smb_server(struct ksmbd_work *work)
 	return 0;
 }
 
-bool ksmbd_pdu_size_has_room(unsigned int pdu)
-{
-	return (pdu >= KSMBD_MIN_SUPPORTED_HEADER_SIZE - 4);
-}
-
 int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work, int info_level,
 				      struct ksmbd_file *dir,
 				      struct ksmbd_dir_info *d_info,
@@ -424,7 +427,7 @@ int ksmbd_extract_shortname(struct ksmbd_conn *conn, const char *longname,
 
 static int __smb2_negotiate(struct ksmbd_conn *conn)
 {
-	return (conn->dialect >= SMB20_PROT_ID &&
+	return (conn->dialect >= SMB21_PROT_ID &&
 		conn->dialect <= SMB311_PROT_ID);
 }
 
@@ -454,7 +457,7 @@ int ksmbd_smb_negotiate_common(struct ksmbd_work *work, unsigned int command)
 		}
 	}
 
-	if (command == SMB2_NEGOTIATE_HE) {
+	if (command == SMB2_NEGOTIATE_HE && __smb2_negotiate(conn)) {
 		ret = smb2_handle_negotiate(work);
 		init_smb2_neg_rsp(work);
 		return ret;