diff options
| author | Dmitry Antipov <dmantipov@yandex.ru> | 2023-11-20 14:05:08 +0300 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2023-11-27 16:24:56 -0800 |
| commit | 4e86f32a13af1970d21be94f659cae56bbe487ee (patch) | |
| tree | 63914b7a840acbb2d9c517545fc0aefc9782b73c | |
| parent | 9099184dec26669bea16ab86e586ad0f90aa7197 (diff) | |
| download | linux-xfs-4e86f32a13af1970d21be94f659cae56bbe487ee.tar.gz | |
uapi: propagate __struct_group() attributes to the container union
Recently the kernel test robot has reported an ARM-specific BUILD_BUG_ON()
in an old and unmaintained wil6210 wireless driver. The problem comes from
the structure packing rules of old ARM ABI ('-mabi=apcs-gnu'). For example,
the following structure is packed to 18 bytes instead of 16:
struct poorly_packed {
unsigned int a;
unsigned int b;
unsigned short c;
union {
struct {
unsigned short d;
unsigned int e;
} __attribute__((packed));
struct {
unsigned short d;
unsigned int e;
} __attribute__((packed)) inner;
};
} __attribute__((packed));
To fit it into 16 bytes, it's required to add packed attribute to the
container union as well:
struct poorly_packed {
unsigned int a;
unsigned int b;
unsigned short c;
union {
struct {
unsigned short d;
unsigned int e;
} __attribute__((packed));
struct {
unsigned short d;
unsigned int e;
} __attribute__((packed)) inner;
} __attribute__((packed));
} __attribute__((packed));
Thanks to Andrew Pinski of GCC team for sorting the things out at
https://gcc.gnu.org/pipermail/gcc/2023-November/242888.html.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311150821.cI4yciFE-lkp@intel.com
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Link: https://lore.kernel.org/r/20231120110607.98956-1-dmantipov@yandex.ru
Fixes: 50d7bd38c3aa ("stddef: Introduce struct_group() helper macro")
Signed-off-by: Kees Cook <keescook@chromium.org>
| -rw-r--r-- | include/uapi/linux/stddef.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/uapi/linux/stddef.h b/include/uapi/linux/stddef.h index 5c6c4269f7efe4..2ec6f35cda32e9 100644 --- a/include/uapi/linux/stddef.h +++ b/include/uapi/linux/stddef.h @@ -27,7 +27,7 @@ union { \ struct { MEMBERS } ATTRS; \ struct TAG { MEMBERS } ATTRS NAME; \ - } + } ATTRS #ifdef __cplusplus /* sizeof(struct{}) is 1 in C++, not 0, can't use C version of the macro. */ |