diff options
author | Qian Cai <cai@lca.pw> | 2019-07-30 11:30:33 -0400 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2019-08-03 11:02:46 -0700 |
commit | 5e5412c365a32e452daa762eac36121cb8a370bb (patch) | |
tree | 855156e17fbe0b130f12916195d0e266d1eb4f3f | |
parent | 59c0b47a1e11b5e81ab1dfd13579c9fbdb02f0b4 (diff) |
net/socket: fix GCC8+ Wpacked-not-aligned warnings
There are a lot of those warnings with GCC8+ 64-bit,
In file included from ./include/linux/sctp.h:42,
from net/core/skbuff.c:47:
./include/uapi/linux/sctp.h:395:1: warning: alignment 4 of 'struct
sctp_paddr_change' is less than 8 [-Wpacked-not-aligned]
} __attribute__((packed, aligned(4)));
^
./include/uapi/linux/sctp.h:728:1: warning: alignment 4 of 'struct
sctp_setpeerprim' is less than 8 [-Wpacked-not-aligned]
} __attribute__((packed, aligned(4)));
^
./include/uapi/linux/sctp.h:727:26: warning: 'sspp_addr' offset 4 in
'struct sctp_setpeerprim' isn't aligned to 8 [-Wpacked-not-aligned]
struct sockaddr_storage sspp_addr;
^~~~~~~~~
./include/uapi/linux/sctp.h:741:1: warning: alignment 4 of 'struct
sctp_prim' is less than 8 [-Wpacked-not-aligned]
} __attribute__((packed, aligned(4)));
^
./include/uapi/linux/sctp.h:740:26: warning: 'ssp_addr' offset 4 in
'struct sctp_prim' isn't aligned to 8 [-Wpacked-not-aligned]
struct sockaddr_storage ssp_addr;
^~~~~~~~
./include/uapi/linux/sctp.h:792:1: warning: alignment 4 of 'struct
sctp_paddrparams' is less than 8 [-Wpacked-not-aligned]
} __attribute__((packed, aligned(4)));
^
./include/uapi/linux/sctp.h:784:26: warning: 'spp_address' offset 4 in
'struct sctp_paddrparams' isn't aligned to 8 [-Wpacked-not-aligned]
struct sockaddr_storage spp_address;
^~~~~~~~~~~
./include/uapi/linux/sctp.h:905:1: warning: alignment 4 of 'struct
sctp_paddrinfo' is less than 8 [-Wpacked-not-aligned]
} __attribute__((packed, aligned(4)));
^
./include/uapi/linux/sctp.h:899:26: warning: 'spinfo_address' offset 4
in 'struct sctp_paddrinfo' isn't aligned to 8 [-Wpacked-not-aligned]
struct sockaddr_storage spinfo_address;
^~~~~~~~~~~~~~
This is because the commit 20c9c825b12f ("[SCTP] Fix SCTP socket options
to work with 32-bit apps on 64-bit kernels.") added "packed, aligned(4)"
GCC attributes to some structures but one of the members, i.e, "struct
sockaddr_storage" in those structures has the attribute,
"aligned(__alignof__ (struct sockaddr *)" which is 8-byte on 64-bit
systems, so the commit overwrites the designed alignments for
"sockaddr_storage".
To fix this, "struct sockaddr_storage" needs to be aligned to 4-byte as
it is only used in those packed sctp structure which is part of UAPI,
and "struct __kernel_sockaddr_storage" is used in some other
places of UAPI that need not to change alignments in order to not
breaking userspace.
Use an implicit alignment for "struct __kernel_sockaddr_storage" so it
can keep the same alignments as a member in both packed and un-packed
structures without breaking UAPI.
Suggested-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | include/uapi/linux/socket.h | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h index 8eb96021709c..c3409c8ec0dd 100644 --- a/include/uapi/linux/socket.h +++ b/include/uapi/linux/socket.h @@ -6,17 +6,24 @@ * Desired design of maximum size and alignment (see RFC2553) */ #define _K_SS_MAXSIZE 128 /* Implementation specific max size */ -#define _K_SS_ALIGNSIZE (__alignof__ (struct sockaddr *)) - /* Implementation specific desired alignment */ typedef unsigned short __kernel_sa_family_t; +/* + * The definition uses anonymous union and struct in order to control the + * default alignment. + */ struct __kernel_sockaddr_storage { - __kernel_sa_family_t ss_family; /* address family */ - /* Following field(s) are implementation specific */ - char __data[_K_SS_MAXSIZE - sizeof(unsigned short)]; + union { + struct { + __kernel_sa_family_t ss_family; /* address family */ + /* Following field(s) are implementation specific */ + char __data[_K_SS_MAXSIZE - sizeof(unsigned short)]; /* space to achieve desired size, */ /* _SS_MAXSIZE value minus size of ss_family */ -} __attribute__ ((aligned(_K_SS_ALIGNSIZE))); /* force desired alignment */ + }; + void *__align; /* implementation specific desired alignment */ + }; +}; #endif /* _UAPI_LINUX_SOCKET_H */ |