Re: [PATCH v2] sparc: mdesc: Fix compile error seen with gcc 11.x

[Arnd Bergmann]

On Wed, Sep 15, 2021 at 12:47 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> sparc64 images fail to compile with gcc 11.x, reporting the following
> errors.
>
> arch/sparc/kernel/mdesc.c:647:22: error:
>         'strcmp' reading 1 or more bytes from a region of size 0
> arch/sparc/kernel/mdesc.c:692:22: error:
>         'strcmp' reading 1 or more bytes from a region of size 0
> arch/sparc/kernel/mdesc.c:719:21:
>         error: 'strcmp' reading 1 or more bytes from a region of size 0
>
> The underlying problem is that node_block() returns a pointer beyond
> the end of struct mdesc_hdr. gcc 11.x detects that and reports the error.
> Adding an additional zero-length field to struct mdesc_hdr and pointing
> to that field fixes the problem.
>
> Cc: Arnd Bergmann <arnd@xxxxxxxxxx>
> Cc: David Laight <David.Laight@xxxxxxxxxx>
> Cc: Anatoly Pugachev <matorola@xxxxxxxxx>
> Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> v2: data[0] => data[]
>
> I am not sure if there was agreement to accept this patch or not, but
> I was asked to resend it with the above change, so here it is. An open
> question was if it is acceptable to have a structure named xxx_hdr
> include an element pointing to the data following that header.
>

Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>