include/linux/netlink.h:116:13: warning: 'sfc: Unsupported: only suppo...' directive output truncated writing 104 bytes into a region of size 80

From: kernel test robot
Date: Thu Oct 19 2023 - 09:26:13 EST


tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: dd72f9c7e512da377074d47d990564959b772643
commit: 66f728872636e1167aedc5a18be6760083911900 sfc: add decrement ttl by offloading set ipv4 ttl actions
date: 8 weeks ago
config: x86_64-randconfig-x013-20230730 (https://download.01.org/0day-ci/archive/20231019/202310192117.YEwbmOWC-lkp@xxxxxxxxx/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231019/202310192117.YEwbmOWC-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310192117.YEwbmOWC-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

In file included from include/uapi/linux/neighbour.h:6,
from include/linux/netdevice.h:45,
from include/net/sch_generic.h:5,
from include/net/pkt_cls.h:7,
from drivers/net/ethernet/sfc/tc.c:12:
drivers/net/ethernet/sfc/tc.c: In function 'efx_tc_mangle':
>> include/linux/netlink.h:116:13: warning: 'sfc: Unsupported: only suppo...' directive output truncated writing 104 bytes into a region of size 80 [-Wformat-truncation=]
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:1155:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
1155 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:116:13: note: directive argument in the range [0, 254]
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:1155:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
1155 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:116:13: note: 'snprintf' output between 107 and 110 bytes into a destination of size 80
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:1155:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
1155 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c: In function 'efx_tc_flower_record_encap_match':
include/linux/netlink.h:116:13: warning: ' conflicts with existing pse...' directive output truncated writing 53 bytes into a region of size between 28 and 33 [-Wformat-truncation=]
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:632:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
632 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:116:13: note: directive argument in the range [0, 65535]
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:632:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
632 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:116:13: note: 'snprintf' output between 102 and 112 bytes into a destination of size 80
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:632:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
632 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:116:13: warning: ' conflicts with existing pse...' directive output truncated writing 57 bytes into a region of size 39 [-Wformat-truncation=]
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:625:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
625 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:116:13: note: directive argument in the range [0, 255]
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:625:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
625 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:116:13: note: 'snprintf' output 103 bytes into a destination of size 80
116 | if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | "%s" fmt "%s", "", ##args, "") >= \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/netlink.h:131:9: note: in expansion of macro 'NL_SET_ERR_MSG_FMT'
131 | NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
| ^~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc.c:625:33: note: in expansion of macro 'NL_SET_ERR_MSG_FMT_MOD'
625 | NL_SET_ERR_MSG_FMT_MOD(extack,
| ^~~~~~~~~~~~~~~~~~~~~~


vim +116 include/linux/netlink.h

2d4bc93368f5a0 Johannes Berg 2017-04-12 107
51c352bdbcd23d Edward Cree 2022-10-18 108 /* We splice fmt with %s at each end even in the snprintf so that both calls
51c352bdbcd23d Edward Cree 2022-10-18 109 * can use the same string constant, avoiding its duplication in .ro
51c352bdbcd23d Edward Cree 2022-10-18 110 */
51c352bdbcd23d Edward Cree 2022-10-18 111 #define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \
51c352bdbcd23d Edward Cree 2022-10-18 112 struct netlink_ext_ack *__extack = (extack); \
51c352bdbcd23d Edward Cree 2022-10-18 113 \
51c352bdbcd23d Edward Cree 2022-10-18 114 if (!__extack) \
51c352bdbcd23d Edward Cree 2022-10-18 115 break; \
51c352bdbcd23d Edward Cree 2022-10-18 @116 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
51c352bdbcd23d Edward Cree 2022-10-18 117 "%s" fmt "%s", "", ##args, "") >= \
51c352bdbcd23d Edward Cree 2022-10-18 118 NETLINK_MAX_FMTMSG_LEN) \
51c352bdbcd23d Edward Cree 2022-10-18 119 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \
51c352bdbcd23d Edward Cree 2022-10-18 120 ##args, "\n"); \
51c352bdbcd23d Edward Cree 2022-10-18 121 \
51c352bdbcd23d Edward Cree 2022-10-18 122 do_trace_netlink_extack(__extack->_msg_buf); \
51c352bdbcd23d Edward Cree 2022-10-18 123 \
51c352bdbcd23d Edward Cree 2022-10-18 124 __extack->_msg = __extack->_msg_buf; \
51c352bdbcd23d Edward Cree 2022-10-18 125 } while (0)
51c352bdbcd23d Edward Cree 2022-10-18 126

:::::: The code at line 116 was first introduced by commit
:::::: 51c352bdbcd23d7ce46b06c1e64c82754dc44044 netlink: add support for formatted extack messages

:::::: TO: Edward Cree <ecree.xilinx@xxxxxxxxx>
:::::: CC: Jakub Kicinski <kuba@xxxxxxxxxx>

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