Messages in this thread | | | From | Jann Horn <> | Date | Fri, 6 Jan 2023 14:19:34 +0100 | Subject | Re: [PATCH v3] ethtool: Replace 0-length array with flexible array |
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On Fri, Jan 6, 2023 at 5:28 AM Kees Cook <keescook@chromium.org> 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@davemloft.net> > Cc: Jakub Kicinski <kuba@kernel.org> > Cc: Andrew Lunn <andrew@lunn.ch> > Cc: kernel test robot <lkp@intel.com> > Cc: Oleksij Rempel <linux@rempel-privat.de> > Cc: Sean Anderson <sean.anderson@seco.com> > Cc: Alexandru Tachici <alexandru.tachici@analog.com> > Cc: Amit Cohen <amcohen@nvidia.com> > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > Cc: Vincent Mailhol <mailhol.vincent@wanadoo.fr> > Cc: netdev@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > v3: don't use helper (vincent) > v2: https://lore.kernel.org/lkml/20230105233420.gonna.036-kees@kernel.org > --- > include/uapi/linux/ethtool.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h > index 58e587ba0450..3135fa0ba9a4 100644 > --- a/include/uapi/linux/ethtool.h > +++ b/include/uapi/linux/ethtool.h > @@ -1183,7 +1183,7 @@ struct ethtool_rxnfc { > __u32 rule_cnt; > __u32 rss_context; > }; > - __u32 rule_locs[0]; > + __u32 rule_locs[];
Stupid question: Is this syntax allowed in UAPI headers despite not being part of standard C90 or C++? Are we relying on all C/C++ compilers for pre-C99 having gcc/clang extensions?
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