Re: [PATCH v3] ethtool: Replace 0-length array with flexible array

[Kees Cook]

On Fri, Jan 06, 2023 at 02:47:35PM +0900, Vincent MAILHOL wrote:
> On Fri. 6 Jan 2023 at 13:28, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> > Zero-length arrays are deprecated[1]. Replace struct ethtool_rxnfc's
> > "rule_locs" 0-length array with a flexible array. Detected with GCC 13,
> > using -fstrict-flex-arrays=3:
> >
> > net/ethtool/common.c: In function 'ethtool_get_max_rxnfc_channel':
> > net/ethtool/common.c:558:55: warning: array subscript i is outside array bounds of '__u32[0]' {aka 'unsigned int[]'} [-Warray-bounds=]
> >   558 |                         .fs.location = info->rule_locs[i],
> >       |                                        ~~~~~~~~~~~~~~~^~~
> > In file included from include/linux/ethtool.h:19,
> >                  from include/uapi/linux/ethtool_netlink.h:12,
> >                  from include/linux/ethtool_netlink.h:6,
> >                  from net/ethtool/common.c:3:
> > include/uapi/linux/ethtool.h:1186:41: note: while referencing
> > 'rule_locs'
> >  1186 |         __u32                           rule_locs[0];
> >       |                                         ^~~~~~~~~
> >
> > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays
> >
> > Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> > Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> > Cc: Andrew Lunn <andrew@xxxxxxx>
> > Cc: kernel test robot <lkp@xxxxxxxxx>
> > Cc: Oleksij Rempel <linux@xxxxxxxxxxxxxxxx>
> > Cc: Sean Anderson <sean.anderson@xxxxxxxx>
> > Cc: Alexandru Tachici <alexandru.tachici@xxxxxxxxxx>
> > Cc: Amit Cohen <amcohen@xxxxxxxxxx>
> > Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx>
> > Cc: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
> > Cc: netdev@xxxxxxxxxxxxxxx
> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> > ---
> > v3: don't use helper (vincent)
> 
> v1: https://lore.kernel.org/all/20230105214126.never.757-kees@xxxxxxxxxx
>                                                ^^^^^
> > v2: https://lore.kernel.org/lkml/20230105233420.gonna.036-kees@xxxxxxxxxx
>                                                   ^^^^^
> v3: https://lore.kernel.org/netdev/20230106042844.give.885-kees@xxxxxxxxxx
>                                                   ^^^^
> 
> Seriously... :)

Hurray! Someone noticed and it's not even April yet. :) *celebrate*

-Kees

-- 
Kees Cook