linux-kernel - Re: [PATCH 2/6] wifi: ath10k: use flexible arrays for WMI start scan TLVs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <202312131111.256FE1A@keescook>
Date:   Wed, 13 Dec 2023 11:11:37 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Jeff Johnson <quic_jjohnson@...cinc.com>
Cc:     Kalle Valo <kvalo@...nel.org>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        ath10k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] wifi: ath10k: use flexible arrays for WMI start scan
 TLVs

On Wed, Dec 13, 2023 at 09:06:40AM -0800, Jeff Johnson wrote:
> Currently ath10k defines the following struct:
> 	struct wmi_start_scan_tlvs {
> 		u8 tlvs[0];
> 	} __packed;
> 
> Per the guidance in [1] this should be a flexible array. However, a
> direct replace to u8 tlvs[] results in the compilation error:
>        flexible array member in a struct with no named members
> 
> This is because C99 6.7.2.1 (16) requires that a structure containing
> a flexible array member must have more than one named member.
> 
> So rather than defining a separate struct wmi_start_scan_tlvs which
> contains the flexible tlvs[] array, just define the tlvs[] array where
> struct wmi_start_scan_tlvs is being used.
> 
> No functional changes, compile tested only.
> 
> [1] https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays
> 
> Signed-off-by: Jeff Johnson <quic_jjohnson@...cinc.com>

Yeah, this too looks like the right approach: keeping the flex array
close instead of externalized into a no-op struct.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook