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Date: Thu, 11 Apr 2024 09:35:42 -0600
From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Steve French <sfrench@samba.org>, Paulo Alcantara <pc@manguebit.com>,
	Ronnie Sahlberg <ronniesahlberg@gmail.com>,
	Shyam Prasad N <sprasad@microsoft.com>, Tom Talpey <tom@talpey.com>,
	Bharath SM <bharathsm@microsoft.com>,
	Namjae Jeon <linkinjeon@kernel.org>,
	Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-cifs@vger.kernel.org, samba-technical@lists.samba.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	linux-hardening@vger.kernel.org
Subject: [PATCH][next] smb: smb2pdu.h: Avoid -Wflex-array-member-not-at-end
 warnings
Message-ID: <ZhgDTj1nwLEtSd9h@neat>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.

So, in order to avoid ending up with a flexible-array member in the
middle of multiple other structs, we use the `__struct_group()` helper
to separate the flexible array from the rest of the members in the
flexible structure, and use the tagged `struct create_context_hdr`
instead of `struct create_context`.

So, with these changes, fix 51 of the following warnings[1]:

fs/smb/client/../common/smb2pdu.h:1225:31: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Link: https://gist.github.com/GustavoARSilva/772526a39be3dd4db39e71497f0a9893 [1]
Link: https://github.com/KSPP/linux/issues/202
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 fs/smb/client/smb2pdu.h | 12 ++++++------
 fs/smb/common/smb2pdu.h | 33 ++++++++++++++++++---------------
 fs/smb/server/smb2pdu.h | 18 +++++++++---------
 3 files changed, 33 insertions(+), 30 deletions(-)

diff --git a/fs/smb/client/smb2pdu.h b/fs/smb/client/smb2pdu.h
index c72a3b2886b7..1a02bd9e0c00 100644
--- a/fs/smb/client/smb2pdu.h
+++ b/fs/smb/client/smb2pdu.h
@@ -145,7 +145,7 @@ struct durable_context_v2 {
 } __packed;
 
 struct create_durable_v2 {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	struct durable_context_v2 dcontext;
 } __packed;
@@ -167,7 +167,7 @@ struct durable_reconnect_context_v2_rsp {
 } __packed;
 
 struct create_durable_handle_reconnect_v2 {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	struct durable_reconnect_context_v2 dcontext;
 	__u8   Pad[4];
@@ -175,7 +175,7 @@ struct create_durable_handle_reconnect_v2 {
 
 /* See MS-SMB2 2.2.13.2.5 */
 struct crt_twarp_ctxt {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8	Name[8];
 	__le64	Timestamp;
 
@@ -183,12 +183,12 @@ struct crt_twarp_ctxt {
 
 /* See MS-SMB2 2.2.13.2.9 */
 struct crt_query_id_ctxt {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8	Name[8];
 } __packed;
 
 struct crt_sd_ctxt {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8	Name[8];
 	struct smb3_sd sd;
 } __packed;
@@ -415,7 +415,7 @@ struct smb2_posix_info_parsed {
 };
 
 struct smb2_create_ea_ctx {
-	struct create_context ctx;
+	struct create_context_hdr ctx;
 	__u8 name[8];
 	struct smb2_file_full_ea_info ea;
 } __packed;
diff --git a/fs/smb/common/smb2pdu.h b/fs/smb/common/smb2pdu.h
index 1b594307c9d5..eab9d49c63ba 100644
--- a/fs/smb/common/smb2pdu.h
+++ b/fs/smb/common/smb2pdu.h
@@ -1171,12 +1171,15 @@ struct smb2_server_client_notification {
 #define SMB2_CREATE_FLAG_REPARSEPOINT 0x01
 
 struct create_context {
-	__le32 Next;
-	__le16 NameOffset;
-	__le16 NameLength;
-	__le16 Reserved;
-	__le16 DataOffset;
-	__le32 DataLength;
+	/* New members must be added within the struct_group() macro below. */
+	__struct_group(create_context_hdr, hdr, __packed,
+		__le32 Next;
+		__le16 NameOffset;
+		__le16 NameLength;
+		__le16 Reserved;
+		__le16 DataOffset;
+		__le32 DataLength;
+	);
 	__u8 Buffer[];
 } __packed;
 
@@ -1222,7 +1225,7 @@ struct smb2_create_rsp {
 } __packed;
 
 struct create_posix {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8    Name[16];
 	__le32  Mode;
 	__u32   Reserved;
@@ -1230,7 +1233,7 @@ struct create_posix {
 
 /* See MS-SMB2 2.2.13.2.3 and MS-SMB2 2.2.13.2.4 */
 struct create_durable {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	union {
 		__u8  Reserved[16];
@@ -1243,14 +1246,14 @@ struct create_durable {
 
 /* See MS-SMB2 2.2.13.2.5 */
 struct create_mxac_req {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	__le64 Timestamp;
 } __packed;
 
 /* See MS-SMB2 2.2.14.2.5 */
 struct create_mxac_rsp {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	__le32 QueryStatus;
 	__le32 MaximalAccess;
@@ -1286,13 +1289,13 @@ struct lease_context_v2 {
 } __packed;
 
 struct create_lease {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	struct lease_context lcontext;
 } __packed;
 
 struct create_lease_v2 {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	struct lease_context_v2 lcontext;
 	__u8   Pad[4];
@@ -1300,7 +1303,7 @@ struct create_lease_v2 {
 
 /* See MS-SMB2 2.2.14.2.9 */
 struct create_disk_id_rsp {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	__le64 DiskFileId;
 	__le64 VolumeId;
@@ -1309,7 +1312,7 @@ struct create_disk_id_rsp {
 
 /* See MS-SMB2 2.2.13.2.13 */
 struct create_app_inst_id {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8 Name[16];
 	__le32 StructureSize; /* Must be 20 */
 	__u16 Reserved;
@@ -1318,7 +1321,7 @@ struct create_app_inst_id {
 
 /* See MS-SMB2 2.2.13.2.15 */
 struct create_app_inst_id_vers {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8 Name[16];
 	__le32 StructureSize; /* Must be 24 */
 	__u16 Reserved;
diff --git a/fs/smb/server/smb2pdu.h b/fs/smb/server/smb2pdu.h
index bd1d2a0e9203..643f5e1cfe35 100644
--- a/fs/smb/server/smb2pdu.h
+++ b/fs/smb/server/smb2pdu.h
@@ -64,7 +64,7 @@ struct preauth_integrity_info {
 #define SMB2_SESSION_TIMEOUT		(10 * HZ)
 
 struct create_durable_req_v2 {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	__le32 Timeout;
 	__le32 Flags;
@@ -73,7 +73,7 @@ struct create_durable_req_v2 {
 } __packed;
 
 struct create_durable_reconn_req {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	union {
 		__u8  Reserved[16];
@@ -85,7 +85,7 @@ struct create_durable_reconn_req {
 } __packed;
 
 struct create_durable_reconn_v2_req {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	struct {
 		__u64 PersistentFileId;
@@ -96,13 +96,13 @@ struct create_durable_reconn_v2_req {
 } __packed;
 
 struct create_alloc_size_req {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	__le64 AllocationSize;
 } __packed;
 
 struct create_durable_rsp {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	union {
 		__u8  Reserved[8];
@@ -114,7 +114,7 @@ struct create_durable_rsp {
 /* Flags */
 #define SMB2_DHANDLE_FLAG_PERSISTENT	0x00000002
 struct create_durable_v2_rsp {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	__le32 Timeout;
 	__le32 Flags;
@@ -122,7 +122,7 @@ struct create_durable_v2_rsp {
 
 /* equivalent of the contents of SMB3.1.1 POSIX open context response */
 struct create_posix_rsp {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8    Name[16];
 	__le32 nlink;
 	__le32 reparse_tag;
@@ -381,13 +381,13 @@ struct smb2_ea_info {
 } __packed; /* level 15 Query */
 
 struct create_ea_buf_req {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	struct smb2_ea_info ea;
 } __packed;
 
 struct create_sd_buf_req {
-	struct create_context ccontext;
+	struct create_context_hdr ccontext;
 	__u8   Name[8];
 	struct smb_ntsd ntsd;
 } __packed;
-- 
2.34.1