| Message ID | ZBTUB/kJYQxq/6Cj@work (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [next] wifi: mt76: mt7921: Replace fake flex-arrays with flexible-array members | expand |
On Fri, Mar 17, 2023 at 02:56:39PM -0600, Gustavo A. R. Silva wrote: > Zero-length arrays as fake flexible arrays are deprecated and we are > moving towards adopting C99 flexible-array members instead. > > Address the following warnings found with GCC-13 and > -fstrict-flex-arrays=3 enabled: > drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:266:25: warning: array subscript 0 is outside array bounds of ‘struct mt7921_asar_dyn_limit_v2[0]’ [-Warray-bounds=] > drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:263:25: warning: array subscript 0 is outside array bounds of ‘struct mt7921_asar_dyn_limit[0]’ [-Warray-bounds=] > drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:223:28: warning: array subscript <unknown> is outside array bounds of ‘struct mt7921_asar_geo_limit_v2[0]’ [-Warray-bounds=] > drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:220:28: warning: array subscript <unknown> is outside array bounds of ‘struct mt7921_asar_geo_limit[0]’ [-Warray-bounds=] > drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:334:37: warning: array subscript i is outside array bounds of ‘u8[0]’ {aka ‘unsigned char[]’} [-Warray-bounds=] > > Notice that the DECLARE_FLEX_ARRAY() helper allows for flexible-array > members in unions. > > This helps with the ongoing efforts to tighten the FORTIFY_SOURCE > routines on memcpy() and help us make progress towards globally > enabling -fstrict-flex-arrays=3 [1]. > > Link: https://github.com/KSPP/linux/issues/21 > Link: https://github.com/KSPP/linux/issues/272 > Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1] > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- > drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h b/drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h > index 35268b0890ad..6f2c4a572572 100644 > --- a/drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h > +++ b/drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h ... > @@ -69,7 +69,7 @@ struct mt7921_asar_geo_v2 { > u8 version; > u8 rsvd; > u8 nr_tbl; > - struct mt7921_asar_geo_limit_v2 tbl[0]; > + DECLARE_FLEX_ARRAY(struct mt7921_asar_geo_limit_v2, tbl); > } __packed; > > struct mt7921_asar_cl { > @@ -85,7 +85,7 @@ struct mt7921_asar_fg { > u8 rsvd; > u8 nr_flag; > u8 rsvd1; > - u8 flag[0]; > + u8 flag[]; I am curious to know why DECLARE_FLEX_ARRAY isn't used here. > } __packed; > > struct mt7921_acpi_sar { > -- > 2.34.1 >
On Mon, Mar 20, 2023 at 03:56:54PM +0100, Simon Horman wrote: > > struct mt7921_asar_cl { > > @@ -85,7 +85,7 @@ struct mt7921_asar_fg { > > u8 rsvd; > > u8 nr_flag; > > u8 rsvd1; > > - u8 flag[0]; > > + u8 flag[]; > > I am curious to know why DECLARE_FLEX_ARRAY isn't used here. In contrast to the other structs, there is no object of type struct mt7921_asar_fg declared in a union: 91 struct mt7921_acpi_sar { 92 u8 ver; 93 union { 94 struct mt7921_asar_dyn *dyn; 95 struct mt7921_asar_dyn_v2 *dyn_v2; 96 }; 97 union { 98 struct mt7921_asar_geo *geo; 99 struct mt7921_asar_geo_v2 *geo_v2; 100 }; 101 struct mt7921_asar_cl *countrylist; 102 struct mt7921_asar_fg *fg; 103 }; The DECLARE_FLEX_ARRAY() helper was created to declare flex-array members in unions or alone in structs[1]. -- Gustavo [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays
On Mon, Mar 20, 2023 at 01:26:49PM -0600, Gustavo A. R. Silva wrote: > On Mon, Mar 20, 2023 at 03:56:54PM +0100, Simon Horman wrote: > > > struct mt7921_asar_cl { > > > @@ -85,7 +85,7 @@ struct mt7921_asar_fg { > > > u8 rsvd; > > > u8 nr_flag; > > > u8 rsvd1; > > > - u8 flag[0]; > > > + u8 flag[]; > > > > I am curious to know why DECLARE_FLEX_ARRAY isn't used here. > > In contrast to the other structs, there is no object of type struct > mt7921_asar_fg declared in a union: > > 91 struct mt7921_acpi_sar { > 92 u8 ver; > 93 union { > 94 struct mt7921_asar_dyn *dyn; > 95 struct mt7921_asar_dyn_v2 *dyn_v2; > 96 }; > 97 union { > 98 struct mt7921_asar_geo *geo; > 99 struct mt7921_asar_geo_v2 *geo_v2; > 100 }; > 101 struct mt7921_asar_cl *countrylist; > 102 struct mt7921_asar_fg *fg; > 103 }; > > The DECLARE_FLEX_ARRAY() helper was created to declare flex-array members > in unions or alone in structs[1]. Thanks for the clarification, much appreciated. FWIIW, with this information I'm happy with this patch. Reviewed-by: Simon Horman <simon.horman@corigine.com>
Hi all, Friendly ping: who can take this, please?
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h b/drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h index 35268b0890ad..6f2c4a572572 100644 --- a/drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h +++ b/drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h @@ -24,7 +24,7 @@ struct mt7921_asar_dyn { u8 names[4]; u8 enable; u8 nr_tbl; - struct mt7921_asar_dyn_limit tbl[0]; + DECLARE_FLEX_ARRAY(struct mt7921_asar_dyn_limit, tbl); } __packed; struct mt7921_asar_dyn_limit_v2 { @@ -37,7 +37,7 @@ struct mt7921_asar_dyn_v2 { u8 enable; u8 rsvd; u8 nr_tbl; - struct mt7921_asar_dyn_limit_v2 tbl[0]; + DECLARE_FLEX_ARRAY(struct mt7921_asar_dyn_limit_v2, tbl); } __packed; struct mt7921_asar_geo_band { @@ -55,7 +55,7 @@ struct mt7921_asar_geo { u8 names[4]; u8 version; u8 nr_tbl; - struct mt7921_asar_geo_limit tbl[0]; + DECLARE_FLEX_ARRAY(struct mt7921_asar_geo_limit, tbl); } __packed; struct mt7921_asar_geo_limit_v2 { @@ -69,7 +69,7 @@ struct mt7921_asar_geo_v2 { u8 version; u8 rsvd; u8 nr_tbl; - struct mt7921_asar_geo_limit_v2 tbl[0]; + DECLARE_FLEX_ARRAY(struct mt7921_asar_geo_limit_v2, tbl); } __packed; struct mt7921_asar_cl { @@ -85,7 +85,7 @@ struct mt7921_asar_fg { u8 rsvd; u8 nr_flag; u8 rsvd1; - u8 flag[0]; + u8 flag[]; } __packed; struct mt7921_acpi_sar {
Zero-length arrays as fake flexible arrays are deprecated and we are moving towards adopting C99 flexible-array members instead. Address the following warnings found with GCC-13 and -fstrict-flex-arrays=3 enabled: drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:266:25: warning: array subscript 0 is outside array bounds of ‘struct mt7921_asar_dyn_limit_v2[0]’ [-Warray-bounds=] drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:263:25: warning: array subscript 0 is outside array bounds of ‘struct mt7921_asar_dyn_limit[0]’ [-Warray-bounds=] drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:223:28: warning: array subscript <unknown> is outside array bounds of ‘struct mt7921_asar_geo_limit_v2[0]’ [-Warray-bounds=] drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:220:28: warning: array subscript <unknown> is outside array bounds of ‘struct mt7921_asar_geo_limit[0]’ [-Warray-bounds=] drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.c:334:37: warning: array subscript i is outside array bounds of ‘u8[0]’ {aka ‘unsigned char[]’} [-Warray-bounds=] Notice that the DECLARE_FLEX_ARRAY() helper allows for flexible-array members in unions. This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines on memcpy() and help us make progress towards globally enabling -fstrict-flex-arrays=3 [1]. Link: https://github.com/KSPP/linux/issues/21 Link: https://github.com/KSPP/linux/issues/272 Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1] Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- drivers/net/wireless/mediatek/mt76/mt7921/acpi_sar.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)