Re: [PATCH][next] smb: smb2pdu.h: Avoid -Wflex-array-member-not-at-end warnings

From: Steve French
Date: Tue Apr 23 2024 - 17:09:52 EST

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On Tue, Apr 23, 2024 at 3:48 PM Gustavo A. R. Silva
<gustavo@xxxxxxxxxxxxxx> wrote:
>
>
>
> On 23/04/24 14:15, Steve French wrote:
> > This looks reasonably safe (running the usual regression tests on it now).
> >
> > Reminds me though that we have to be careful (e.g. the recent fix for
> > regression caused by cleanup).
>
> mmh... it seems that the offending commit was never CC'd to the linux-hardening
> list, hence it wasn't reviewed by us.
>
> After reviewing both, the offending commit and the fix, both seem to be wrong.
>
> for __packed structs, you should use __struct_group():
>
> __struct_group(network_open_info, group_name, __packed, struct_members);
>
> The _packed in the commit 0268a7cc7fdc is not an attribute, it's the name
> for the group. So, it's not actually doing what the submitter thinks it does.

Do you want to submit a followup fix to fix this? Or let Namjae fix it?

> > Thoughts about whether should be sent in rc6 or wait till 6.10? 51
> > warnings does sound
> > distracting though so might be worth going in sooner rather than later.
>
> There is actually no hurry. :)
>
> Thanks
> --
> Gustavo
>
> >
> > commit 0268a7cc7fdc47d90b6c18859de7718d5059f6f1
> > Author: Namjae Jeon <linkinjeon@xxxxxxxxxx>
> > Date: Fri Apr 19 23:46:34 2024 +0900
> >
> > ksmbd: common: use struct_group_attr instead of struct_group for
> > network_open_info
> >
> > 4byte padding cause the connection issue with the applications of MacOS.
> > smb2_close response size increases by 4 bytes by padding, And the smb
> > client of MacOS check it and stop the connection. This patch use
> > struct_group_attr instead of struct_group for network_open_info to use
> > __packed to avoid padding.
> >
> >
> > On Tue, Apr 23, 2024 at 1:58 PM Gustavo A. R. Silva
> > <gustavo@xxxxxxxxxxxxxx> wrote:
> >>
> >> 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@xxxxxxxxxx>
> >>> ---
> >>> 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;
> >>
> >
> >
> > --
> > Thanks,
> >
> > Steve

--
Thanks,

Steve

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