| Message ID | 20250312200700.make.521-kees@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v3] net: macb: Add __nonstring annotations for unterminated strings | expand |
On 3/12/2025 1:07 PM, Kees Cook wrote: > When a character array without a terminating NUL character has a static > initializer, GCC 15's -Wunterminated-string-initialization will only > warn if the array lacks the "nonstring" attribute[1]. Mark the arrays > with __nonstring to correctly identify the char array as "not a C string" > and thereby eliminate the warning: > > In file included from ../drivers/net/ethernet/cadence/macb_main.c:42: > ../drivers/net/ethernet/cadence/macb.h:1070:35: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (33 chars into 32 available) [-Wunterminated-string-initialization] > 1070 | GEM_STAT_TITLE(TX1519CNT, "tx_greater_than_1518_byte_frames"), > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ../drivers/net/ethernet/cadence/macb.h:1050:24: note: in definition of macro 'GEM_STAT_TITLE_BITS' > 1050 | .stat_string = title, \ > | ^~~~~ > ../drivers/net/ethernet/cadence/macb.h:1070:9: note: in expansion of macro 'GEM_STAT_TITLE' > 1070 | GEM_STAT_TITLE(TX1519CNT, "tx_greater_than_1518_byte_frames"), > | ^~~~~~~~~~~~~~ > ../drivers/net/ethernet/cadence/macb.h:1097:35: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (33 chars into 32 available) [-Wunterminated-string-initialization] > 1097 | GEM_STAT_TITLE(RX1519CNT, "rx_greater_than_1518_byte_frames"), > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ../drivers/net/ethernet/cadence/macb.h:1050:24: note: in definition of macro 'GEM_STAT_TITLE_BITS' > 1050 | .stat_string = title, \ > | ^~~~~ > ../drivers/net/ethernet/cadence/macb.h:1097:9: note: in expansion of macro 'GEM_STAT_TITLE' > 1097 | GEM_STAT_TITLE(RX1519CNT, "rx_greater_than_1518_byte_frames"), > | ^~~~~~~~~~~~~~ > > Since these strings are copied with memcpy() they do not need to be > NUL terminated, and can use __nonstring: > > memcpy(p, gem_statistics[i].stat_string, > ETH_GSTRING_LEN); > > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1] > Signed-off-by: Kees Cook <kees@kernel.org> > --- Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> > v3: improve commit message (Bill), drop whitespace change (Bill) > v2: https://lore.kernel.org/lkml/20250311224412.it.153-kees@kernel.org/ > v1: https://lore.kernel.org/lkml/20250310222415.work.815-kees@kernel.org/ > Cc: Nicolas Ferre <nicolas.ferre@microchip.com> > Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev> > Cc: Andrew Lunn <andrew+netdev@lunn.ch> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Eric Dumazet <edumazet@google.com> > Cc: Jakub Kicinski <kuba@kernel.org> > Cc: Paolo Abeni <pabeni@redhat.com> > Cc: netdev@vger.kernel.org > --- > drivers/net/ethernet/cadence/macb.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h > index 2847278d9cd4..d2a4c180d6a6 100644 > --- a/drivers/net/ethernet/cadence/macb.h > +++ b/drivers/net/ethernet/cadence/macb.h > @@ -1027,7 +1027,7 @@ struct gem_stats { > * this register should contribute to. > */ > struct gem_statistic { > - char stat_string[ETH_GSTRING_LEN]; > + char stat_string[ETH_GSTRING_LEN] __nonstring; > int offset; > u32 stat_bits; > };
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h index 2847278d9cd4..d2a4c180d6a6 100644 --- a/drivers/net/ethernet/cadence/macb.h +++ b/drivers/net/ethernet/cadence/macb.h @@ -1027,7 +1027,7 @@ struct gem_stats { * this register should contribute to. */ struct gem_statistic { - char stat_string[ETH_GSTRING_LEN]; + char stat_string[ETH_GSTRING_LEN] __nonstring; int offset; u32 stat_bits; };
When a character array without a terminating NUL character has a static initializer, GCC 15's -Wunterminated-string-initialization will only warn if the array lacks the "nonstring" attribute[1]. Mark the arrays with __nonstring to correctly identify the char array as "not a C string" and thereby eliminate the warning: In file included from ../drivers/net/ethernet/cadence/macb_main.c:42: ../drivers/net/ethernet/cadence/macb.h:1070:35: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (33 chars into 32 available) [-Wunterminated-string-initialization] 1070 | GEM_STAT_TITLE(TX1519CNT, "tx_greater_than_1518_byte_frames"), | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../drivers/net/ethernet/cadence/macb.h:1050:24: note: in definition of macro 'GEM_STAT_TITLE_BITS' 1050 | .stat_string = title, \ | ^~~~~ ../drivers/net/ethernet/cadence/macb.h:1070:9: note: in expansion of macro 'GEM_STAT_TITLE' 1070 | GEM_STAT_TITLE(TX1519CNT, "tx_greater_than_1518_byte_frames"), | ^~~~~~~~~~~~~~ ../drivers/net/ethernet/cadence/macb.h:1097:35: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (33 chars into 32 available) [-Wunterminated-string-initialization] 1097 | GEM_STAT_TITLE(RX1519CNT, "rx_greater_than_1518_byte_frames"), | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../drivers/net/ethernet/cadence/macb.h:1050:24: note: in definition of macro 'GEM_STAT_TITLE_BITS' 1050 | .stat_string = title, \ | ^~~~~ ../drivers/net/ethernet/cadence/macb.h:1097:9: note: in expansion of macro 'GEM_STAT_TITLE' 1097 | GEM_STAT_TITLE(RX1519CNT, "rx_greater_than_1518_byte_frames"), | ^~~~~~~~~~~~~~ Since these strings are copied with memcpy() they do not need to be NUL terminated, and can use __nonstring: memcpy(p, gem_statistics[i].stat_string, ETH_GSTRING_LEN); Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1] Signed-off-by: Kees Cook <kees@kernel.org> --- v3: improve commit message (Bill), drop whitespace change (Bill) v2: https://lore.kernel.org/lkml/20250311224412.it.153-kees@kernel.org/ v1: https://lore.kernel.org/lkml/20250310222415.work.815-kees@kernel.org/ Cc: Nicolas Ferre <nicolas.ferre@microchip.com> Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev> Cc: Andrew Lunn <andrew+netdev@lunn.ch> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: netdev@vger.kernel.org --- drivers/net/ethernet/cadence/macb.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)