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Message-ID: <1166494b-3e34-4919-9998-141540a948b3@embeddedor.com>
Date: Wed, 24 Apr 2024 04:57:07 +1000
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Subject: Re: [PATCH][next] smb: smb2pdu.h: Avoid
 -Wflex-array-member-not-at-end warnings
To: "Gustavo A. R. Silva" <gustavoars@kernel.org>,
 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, linux-hardening@vger.kernel.org,
 Kees Cook <keescook@chromium.org>
References: <ZhgDTj1nwLEtSd9h@neat>
Content-Language: en-US
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <ZhgDTj1nwLEtSd9h@neat>
Content-Type: text/plain; charset=UTF-8; format=flowed
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Hi all,

Friendly ping: who can take this, please?

Thanks
--
Gustavo

On 11/04/24 09:35, Gustavo A. R. Silva wrote:
> -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;