ksmbd: fix potencial out-of-bounds when buffer offset is invalid

I found potencial out-of-bounds when buffer offset fields of a few requests
is invalid. This patch set the minimum value of buffer offset field to
->Buffer offset to validate buffer length.

Cc: stable@vger.kernel.org
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/smb2misc.c

@@ -101,7 +101,9 @@ static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
 		*len = le16_to_cpu(((struct smb2_sess_setup_req *)hdr)->SecurityBufferLength);
 		break;
 	case SMB2_TREE_CONNECT:
-		*off = le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathOffset);
+		*off = max_t(unsigned short int,
+			     le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathOffset),
+			     offsetof(struct smb2_tree_connect_req, Buffer));
 		*len = le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathLength);
 		break;
 	case SMB2_CREATE:
@@ -110,7 +112,6 @@ static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
 			max_t(unsigned short int,
 			      le16_to_cpu(((struct smb2_create_req *)hdr)->NameOffset),
 			      offsetof(struct smb2_create_req, Buffer));
-
 		unsigned short int name_len =
 			le16_to_cpu(((struct smb2_create_req *)hdr)->NameLength);
 
@@ -131,11 +132,15 @@ static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
 		break;
 	}
 	case SMB2_QUERY_INFO:
-		*off = le16_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferOffset);
+		*off = max_t(unsigned int,
+			     le16_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferOffset),
+			     offsetof(struct smb2_query_info_req, Buffer));
 		*len = le32_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferLength);
 		break;
 	case SMB2_SET_INFO:
-		*off = le16_to_cpu(((struct smb2_set_info_req *)hdr)->BufferOffset);
+		*off = max_t(unsigned int,
+			     le16_to_cpu(((struct smb2_set_info_req *)hdr)->BufferOffset),
+			     offsetof(struct smb2_set_info_req, Buffer));
 		*len = le32_to_cpu(((struct smb2_set_info_req *)hdr)->BufferLength);
 		break;
 	case SMB2_READ:
@@ -145,7 +150,7 @@ static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
 	case SMB2_WRITE:
 		if (((struct smb2_write_req *)hdr)->DataOffset ||
 		    ((struct smb2_write_req *)hdr)->Length) {
-			*off = max_t(unsigned int,
+			*off = max_t(unsigned short int,
 				     le16_to_cpu(((struct smb2_write_req *)hdr)->DataOffset),
 				     offsetof(struct smb2_write_req, Buffer));
 			*len = le32_to_cpu(((struct smb2_write_req *)hdr)->Length);
@@ -156,7 +161,9 @@ static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
 		*len = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoLength);
 		break;
 	case SMB2_QUERY_DIRECTORY:
-		*off = le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameOffset);
+		*off = max_t(unsigned short int,
+			     le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameOffset),
+			     offsetof(struct smb2_query_directory_req, Buffer));
 		*len = le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameLength);
 		break;
 	case SMB2_LOCK:
@@ -171,7 +178,9 @@ static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
 		break;
 	}
 	case SMB2_IOCTL:
-		*off = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputOffset);
+		*off = max_t(unsigned int,
+			     le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputOffset),
+			     offsetof(struct smb2_ioctl_req, Buffer));
 		*len = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputCount);
 		break;
 	default:

fs/smb/server/smb2pdu.c

@@ -1927,7 +1927,7 @@ int smb2_tree_connect(struct ksmbd_work *work)
 
 	WORK_BUFFERS(work, req, rsp);
 
-	treename = smb_strndup_from_utf16(req->Buffer,
+	treename = smb_strndup_from_utf16((char *)req + le16_to_cpu(req->PathOffset),
 					  le16_to_cpu(req->PathLength), true,
 					  conn->local_nls);
 	if (IS_ERR(treename)) {
@@ -2840,7 +2840,7 @@ int smb2_open(struct ksmbd_work *work)
 			goto err_out2;
 		}
 
-		name = smb2_get_name(req->Buffer,
+		name = smb2_get_name((char *)req + le16_to_cpu(req->NameOffset),
 				     le16_to_cpu(req->NameLength),
 				     work->conn->local_nls);
 		if (IS_ERR(name)) {
@@ -4305,7 +4305,7 @@ int smb2_query_dir(struct ksmbd_work *work)
 	}
 
 	srch_flag = req->Flags;
-	srch_ptr = smb_strndup_from_utf16(req->Buffer,
+	srch_ptr = smb_strndup_from_utf16((char *)req + le16_to_cpu(req->FileNameOffset),
 					  le16_to_cpu(req->FileNameLength), 1,
 					  conn->local_nls);
 	if (IS_ERR(srch_ptr)) {
@@ -4565,7 +4565,8 @@ static int smb2_get_ea(struct ksmbd_work *work, struct ksmbd_file *fp,
 		    sizeof(struct smb2_ea_info_req))
 			return -EINVAL;
 
-		ea_req = (struct smb2_ea_info_req *)req->Buffer;
+		ea_req = (struct smb2_ea_info_req *)((char *)req +
+						     le16_to_cpu(req->InputBufferOffset));
 	} else {
 		/* need to send all EAs, if no specific EA is requested*/
 		if (le32_to_cpu(req->Flags) & SL_RETURN_SINGLE_ENTRY)
@@ -6211,6 +6212,7 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 			      struct ksmbd_share_config *share)
 {
 	unsigned int buf_len = le32_to_cpu(req->BufferLength);
+	char *buffer = (char *)req + le16_to_cpu(req->BufferOffset);
 
 	switch (req->FileInfoClass) {
 	case FILE_BASIC_INFORMATION:
@@ -6218,7 +6220,7 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 		if (buf_len < sizeof(struct smb2_file_basic_info))
 			return -EINVAL;
 
-		return set_file_basic_info(fp, (struct smb2_file_basic_info *)req->Buffer, share);
+		return set_file_basic_info(fp, (struct smb2_file_basic_info *)buffer, share);
 	}
 	case FILE_ALLOCATION_INFORMATION:
 	{
@@ -6226,7 +6228,7 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 			return -EINVAL;
 
 		return set_file_allocation_info(work, fp,
-						(struct smb2_file_alloc_info *)req->Buffer);
+						(struct smb2_file_alloc_info *)buffer);
 	}
 	case FILE_END_OF_FILE_INFORMATION:
 	{
@@ -6234,7 +6236,7 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 			return -EINVAL;
 
 		return set_end_of_file_info(work, fp,
-					    (struct smb2_file_eof_info *)req->Buffer);
+					    (struct smb2_file_eof_info *)buffer);
 	}
 	case FILE_RENAME_INFORMATION:
 	{
@@ -6242,7 +6244,7 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 			return -EINVAL;
 
 		return set_rename_info(work, fp,
-				       (struct smb2_file_rename_info *)req->Buffer,
+				       (struct smb2_file_rename_info *)buffer,
 				       buf_len);
 	}
 	case FILE_LINK_INFORMATION:
@@ -6251,7 +6253,7 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 			return -EINVAL;
 
 		return smb2_create_link(work, work->tcon->share_conf,
-					(struct smb2_file_link_info *)req->Buffer,
+					(struct smb2_file_link_info *)buffer,
 					buf_len, fp->filp,
 					work->conn->local_nls);
 	}
@@ -6261,7 +6263,7 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 			return -EINVAL;
 
 		return set_file_disposition_info(fp,
-						 (struct smb2_file_disposition_info *)req->Buffer);
+						 (struct smb2_file_disposition_info *)buffer);
 	}
 	case FILE_FULL_EA_INFORMATION:
 	{
@@ -6274,7 +6276,7 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 		if (buf_len < sizeof(struct smb2_ea_info))
 			return -EINVAL;
 
-		return smb2_set_ea((struct smb2_ea_info *)req->Buffer,
+		return smb2_set_ea((struct smb2_ea_info *)buffer,
 				   buf_len, &fp->filp->f_path, true);
 	}
 	case FILE_POSITION_INFORMATION:
@@ -6282,14 +6284,14 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 		if (buf_len < sizeof(struct smb2_file_pos_info))
 			return -EINVAL;
 
-		return set_file_position_info(fp, (struct smb2_file_pos_info *)req->Buffer);
+		return set_file_position_info(fp, (struct smb2_file_pos_info *)buffer);
 	}
 	case FILE_MODE_INFORMATION:
 	{
 		if (buf_len < sizeof(struct smb2_file_mode_info))
 			return -EINVAL;
 
-		return set_file_mode_info(fp, (struct smb2_file_mode_info *)req->Buffer);
+		return set_file_mode_info(fp, (struct smb2_file_mode_info *)buffer);
 	}
 	}
 
@@ -6370,7 +6372,7 @@ int smb2_set_info(struct ksmbd_work *work)
 		}
 		rc = smb2_set_info_sec(fp,
 				       le32_to_cpu(req->AdditionalInformation),
-				       req->Buffer,
+				       (char *)req + le16_to_cpu(req->BufferOffset),
 				       le32_to_cpu(req->BufferLength));
 		ksmbd_revert_fsids(work);
 		break;
@@ -7816,7 +7818,7 @@ static int fsctl_pipe_transceive(struct ksmbd_work *work, u64 id,
 				 struct smb2_ioctl_rsp *rsp)
 {
 	struct ksmbd_rpc_command *rpc_resp;
-	char *data_buf = (char *)&req->Buffer[0];
+	char *data_buf = (char *)req + le32_to_cpu(req->InputOffset);
 	int nbytes = 0;
 
 	rpc_resp = ksmbd_rpc_ioctl(work->sess, id, data_buf,
@@ -7929,6 +7931,7 @@ int smb2_ioctl(struct ksmbd_work *work)
 	u64 id = KSMBD_NO_FID;
 	struct ksmbd_conn *conn = work->conn;
 	int ret = 0;
+	char *buffer;
 
 	if (work->next_smb2_rcv_hdr_off) {
 		req = ksmbd_req_buf_next(work);
@@ -7951,6 +7954,8 @@ int smb2_ioctl(struct ksmbd_work *work)
 		goto out;
 	}
 
+	buffer = (char *)req + le32_to_cpu(req->InputOffset);
+
 	cnt_code = le32_to_cpu(req->CtlCode);
 	ret = smb2_calc_max_out_buf_len(work, 48,
 					le32_to_cpu(req->MaxOutputResponse));
@@ -8008,7 +8013,7 @@ int smb2_ioctl(struct ksmbd_work *work)
 		}
 
 		ret = fsctl_validate_negotiate_info(conn,
-			(struct validate_negotiate_info_req *)&req->Buffer[0],
+			(struct validate_negotiate_info_req *)buffer,
 			(struct validate_negotiate_info_rsp *)&rsp->Buffer[0],
 			in_buf_len);
 		if (ret < 0)
@@ -8061,7 +8066,7 @@ int smb2_ioctl(struct ksmbd_work *work)
 		rsp->VolatileFileId = req->VolatileFileId;
 		rsp->PersistentFileId = req->PersistentFileId;
 		fsctl_copychunk(work,
-				(struct copychunk_ioctl_req *)&req->Buffer[0],
+				(struct copychunk_ioctl_req *)buffer,
 				le32_to_cpu(req->CtlCode),
 				le32_to_cpu(req->InputCount),
 				req->VolatileFileId,
@@ -8074,8 +8079,7 @@ int smb2_ioctl(struct ksmbd_work *work)
 			goto out;
 		}
 
-		ret = fsctl_set_sparse(work, id,
-				       (struct file_sparse *)&req->Buffer[0]);
+		ret = fsctl_set_sparse(work, id, (struct file_sparse *)buffer);
 		if (ret < 0)
 			goto out;
 		break;
@@ -8098,7 +8102,7 @@ int smb2_ioctl(struct ksmbd_work *work)
 		}
 
 		zero_data =
-			(struct file_zero_data_information *)&req->Buffer[0];
+			(struct file_zero_data_information *)buffer;
 
 		off = le64_to_cpu(zero_data->FileOffset);
 		bfz = le64_to_cpu(zero_data->BeyondFinalZero);
@@ -8129,7 +8133,7 @@ int smb2_ioctl(struct ksmbd_work *work)
 		}
 
 		ret = fsctl_query_allocated_ranges(work, id,
-			(struct file_allocated_range_buffer *)&req->Buffer[0],
+			(struct file_allocated_range_buffer *)buffer,
 			(struct file_allocated_range_buffer *)&rsp->Buffer[0],
 			out_buf_len /
 			sizeof(struct file_allocated_range_buffer), &nbytes);
@@ -8173,7 +8177,7 @@ int smb2_ioctl(struct ksmbd_work *work)
 			goto out;
 		}
 
-		dup_ext = (struct duplicate_extents_to_file *)&req->Buffer[0];
+		dup_ext = (struct duplicate_extents_to_file *)buffer;
 
 		fp_in = ksmbd_lookup_fd_slow(work, dup_ext->VolatileFileHandle,
 					     dup_ext->PersistentFileHandle);