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Avoid undefined behavior in struct sockaddr

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Problem noted by Philipp Stephani in:
http://lists.gnu.org/archive/html/emacs-devel/2017-05/msg00391.html
* src/conf_post.h (ATTRIBUTE_MAY_ALIAS, DECLARE_POINTER_ALIAS):
New macros.
* src/process.c (conv_sockaddr_to_lisp, conv_lisp_to_sockaddr)
(connect_network_socket, network_interface_info)
(server_accept_connection): Use it when aliasing non-char objects.
This commit is contained in:
Paul Eggert 2017-05-17 13:35:52 -07:00
parent 184d74ce00
commit e54a3b4fde
2 changed files with 31 additions and 14 deletions
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14
src/conf_post.h
View file

@ -263,6 +263,20 @@ extern int emacs_setenv_TZ (char const *);
#define ATTRIBUTE_CONST _GL_ATTRIBUTE_CONST
#define ATTRIBUTE_UNUSED _GL_UNUSED
#if GNUC_PREREQ (3, 3, 0)
# define ATTRIBUTE_MAY_ALIAS __attribute__ ((__may_alias__))
#else
# define ATTRIBUTE_MAY_ALIAS
#endif
/* Declare NAME to be a pointer to an object of type TYPE, initialized
to the address ADDR, which may be of a different type. Accesses
via NAME may alias with other accesses with the traditional
behavior, even if options like gcc -fstrict-aliasing are used. */
#define DECLARE_POINTER_ALIAS(name, type, addr) \
type ATTRIBUTE_MAY_ALIAS *name = (type *) (addr)
#if 3 <= __GNUC__
# define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
#else

31
src/process.c
View file

@ -2476,7 +2476,7 @@ conv_sockaddr_to_lisp (struct sockaddr *sa, ptrdiff_t len)
{
case AF_INET:
{
struct sockaddr_in *sin = (struct sockaddr_in *) sa;
DECLARE_POINTER_ALIAS (sin, struct sockaddr_in, sa);
len = sizeof (sin->sin_addr) + 1;
address = Fmake_vector (make_number (len), Qnil);
p = XVECTOR (address);
@ -2487,8 +2487,8 @@ conv_sockaddr_to_lisp (struct sockaddr *sa, ptrdiff_t len)
#ifdef AF_INET6
case AF_INET6:
{
struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) sa;
uint16_t *ip6 = (uint16_t *) &sin6->sin6_addr;
DECLARE_POINTER_ALIAS (sin6, struct sockaddr_in6, sa);
DECLARE_POINTER_ALIAS (ip6, uint16_t, &sin6->sin6_addr);
len = sizeof (sin6->sin6_addr) / 2 + 1;
address = Fmake_vector (make_number (len), Qnil);
p = XVECTOR (address);
@ -2501,7 +2501,7 @@ conv_sockaddr_to_lisp (struct sockaddr *sa, ptrdiff_t len)
#ifdef HAVE_LOCAL_SOCKETS
case AF_LOCAL:
{
struct sockaddr_un *sockun = (struct sockaddr_un *) sa;
DECLARE_POINTER_ALIAS (sockun, struct sockaddr_un, sa);
ptrdiff_t name_length = len - offsetof (struct sockaddr_un, sun_path);
/* If the first byte is NUL, the name is a Linux abstract
socket name, and the name can contain embedded NULs. If
@ -2612,7 +2612,7 @@ conv_lisp_to_sockaddr (int family, Lisp_Object address, struct sockaddr *sa, int
p = XVECTOR (address);
if (family == AF_INET)
{
struct sockaddr_in *sin = (struct sockaddr_in *) sa;
DECLARE_POINTER_ALIAS (sin, struct sockaddr_in, sa);
len = sizeof (sin->sin_addr) + 1;
hostport = XINT (p->contents[--len]);
sin->sin_port = htons (hostport);
@ -2622,8 +2622,8 @@ conv_lisp_to_sockaddr (int family, Lisp_Object address, struct sockaddr *sa, int
#ifdef AF_INET6
else if (family == AF_INET6)
{
struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) sa;
uint16_t *ip6 = (uint16_t *)&sin6->sin6_addr;
DECLARE_POINTER_ALIAS (sin6, struct sockaddr_in6, sa);
DECLARE_POINTER_ALIAS (ip6, uint16_t, &sin6->sin6_addr);
len = sizeof (sin6->sin6_addr) / 2 + 1;
hostport = XINT (p->contents[--len]);
sin6->sin6_port = htons (hostport);
@ -2645,7 +2645,7 @@ conv_lisp_to_sockaddr (int family, Lisp_Object address, struct sockaddr *sa, int
#ifdef HAVE_LOCAL_SOCKETS
if (family == AF_LOCAL)
{
struct sockaddr_un *sockun = (struct sockaddr_un *) sa;
DECLARE_POINTER_ALIAS (sockun, struct sockaddr_un, sa);
cp = SDATA (address);
for (i = 0; i < sizeof (sockun->sun_path) && *cp; i++)
sockun->sun_path[i] = *cp++;
@ -3436,13 +3436,15 @@ connect_network_socket (Lisp_Object proc, Lisp_Object addrinfos,
== offsetof (struct sockaddr_in6, sin6_port))
&& sizeof (sa1.sin_port) == sizeof (sa6.sin6_port));
#endif
if (getsockname (s, (struct sockaddr *)&sa1, &len1) == 0)
DECLARE_POINTER_ALIAS (psa1, struct sockaddr, &sa1);
if (getsockname (s, psa1, &len1) == 0)
{
Lisp_Object service = make_number (ntohs (sa1.sin_port));
contact = Fplist_put (contact, QCservice, service);
/* Save the port number so that we can stash it in
the process object later. */
((struct sockaddr_in *) sa)->sin_port = sa1.sin_port;
DECLARE_POINTER_ALIAS (psa, struct sockaddr_in, sa);
psa->sin_port = sa1.sin_port;
}
}
#endif
@ -3550,9 +3552,10 @@ connect_network_socket (Lisp_Object proc, Lisp_Object addrinfos,
{
struct sockaddr_storage sa1;
socklen_t len1 = sizeof (sa1);
if (getsockname (s, (struct sockaddr *)&sa1, &len1) == 0)
DECLARE_POINTER_ALIAS (psa1, struct sockaddr, &sa1);
if (getsockname (s, psa1, &len1) == 0)
contact = Fplist_put (contact, QClocal,
conv_sockaddr_to_lisp ((struct sockaddr *)&sa1, len1));
conv_sockaddr_to_lisp (psa1, len1));
}
#endif
}
@ -4401,7 +4404,7 @@ network_interface_info (Lisp_Object ifname)
for (it = ifap; it != NULL; it = it->ifa_next)
{
struct sockaddr_dl *sdl = (struct sockaddr_dl *) it->ifa_addr;
DECLARE_POINTER_ALIAS (sdl, struct sockaddr_dl, it->ifa_addr);
unsigned char linkaddr[6];
int n;
@ -4722,7 +4725,7 @@ server_accept_connection (Lisp_Object server, int channel)
{
args[nargs++] = procname_format_in6;
nargs++;
uint16_t *ip6 = (uint16_t *)&saddr.in6.sin6_addr;
DECLARE_POINTER_ALIAS (ip6, uint16_t, &saddr.in6.sin6_addr);
service = make_number (ntohs (saddr.in.sin_port));
for (int i = 0; i < 8; i++)
args[nargs++] = make_number (ip6[i]);