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Date: Tue, 9 Jan 2024 12:40:59 +0100
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Namjae Jeon <linkinjeon@kernel.org>
Cc: stable@vger.kernel.org, Steve French <sfrench@samba.org>,
	Paulo Alcantara <pc@cjr.nz>, Shyam Prasad N <sprasad@microsoft.com>,
	Tom Talpey <tom@talpey.com>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	linux-cifs@vger.kernel.org, Kees Cook <keescook@chromium.org>,
	Steve French <stfrench@microsoft.com>,
	Steve French <smfrench@gmail.com>
Subject: Re: [PATCH 6.1.y ] smb3: Replace smb2pdu 1-element arrays with
 flex-arrays
Message-ID: <2024010937-eggplant-bauble-d556@gregkh>
References: <CAKYAXd-aYvX9nOZ=gjruv5Mk0eS9ZdF569QBk2YCqEvR_nwxPQ@mail.gmail.com>
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On Tue, Jan 09, 2024 at 04:18:39PM +0900, Namjae Jeon wrote:
> From: Kees Cook <keescook@chromium.org>
> 
> commit eb3e28c1e89b4984308777231887e41aa8a0151f upstream.
> 
> The kernel is globally removing the ambiguous 0-length and 1-element
> arrays in favor of flexible arrays, so that we can gain both compile-time
> and run-time array bounds checking[1].
> 
> Replace the trailing 1-element array with a flexible array in the
> following structures:
> 
> 	struct smb2_err_rsp
> 	struct smb2_tree_connect_req
> 	struct smb2_negotiate_rsp
> 	struct smb2_sess_setup_req
> 	struct smb2_sess_setup_rsp
> 	struct smb2_read_req
> 	struct smb2_read_rsp
> 	struct smb2_write_req
> 	struct smb2_write_rsp
> 	struct smb2_query_directory_req
> 	struct smb2_query_directory_rsp
> 	struct smb2_set_info_req
> 	struct smb2_change_notify_rsp
> 	struct smb2_create_rsp
> 	struct smb2_query_info_req
> 	struct smb2_query_info_rsp
> 
> Replace the trailing 1-element array with a flexible array, but leave
> the existing structure padding:
> 
> 	struct smb2_file_all_info
> 	struct smb2_lock_req
> 
> Adjust all related size calculations to match the changes to sizeof().
> 
> No machine code output or .data section differences are produced after
> these changes.
> 
> [1] For lots of details, see both:
>     https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays
>     https://people.kernel.org/kees/bounded-flexible-arrays-in-c
> 
> Cc: Steve French <sfrench@samba.org>
> Cc: Paulo Alcantara <pc@cjr.nz>
> Cc: Ronnie Sahlberg <lsahlber@redhat.com>
> Cc: Shyam Prasad N <sprasad@microsoft.com>
> Cc: Tom Talpey <tom@talpey.com>
> Cc: Namjae Jeon <linkinjeon@kernel.org>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: linux-cifs@vger.kernel.org
> Cc: samba-technical@lists.samba.org
> Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Steve French <stfrench@microsoft.com>

Thanks for the updated patch, good catch on my mistake in backporting
this.  Now queued up.

greg k-h