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Fix alignment issues in FD passing code

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A char array on the stack is not guaranteed to have more than byte
alignment.  This means that casting it to a 'struct cmsghdr' and
accessing its members may result in unaligned access.  This will
generate SIGBUS on strict alignment architectures like OpenBSD/sparc64.
The solution is to use a union to force proper alignment.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Matthieu Herrb <matthieu@herrb.eu>
This commit is contained in:
Mark Kettenis
2013-11-11 23:18:01 +01:00
parent 81662d2018
commit 8b2c8aabe2
1 changed files with 8 additions and 8 deletions
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16
Xtranssock.c
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@@ -2197,9 +2197,9 @@ TRANS(SocketSendFdInvalid)(XtransConnInfo ciptr, int fd, int do_close)
#define MAX_FDS 128
struct fd_pass {
union fd_pass {
struct cmsghdr cmsghdr;
int fd[MAX_FDS];
char buf[CMSG_SPACE(MAX_FDS * sizeof(int))];
};
#endif /* XTRANS_SEND_FDS */
@@ -2225,13 +2225,13 @@ TRANS(SocketRead) (XtransConnInfo ciptr, char *buf, int size)
.iov_base = buf,
.iov_len = size
};
char cmsgbuf[CMSG_SPACE(sizeof(int) * MAX_FDS)];
union fd_pass cmsgbuf;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = cmsgbuf,
.msg_control = cmsgbuf.buf,
.msg_controllen = CMSG_LEN(MAX_FDS * sizeof(int))
};
@@ -2266,13 +2266,13 @@ TRANS(SocketReadv) (XtransConnInfo ciptr, struct iovec *buf, int size)
#if XTRANS_SEND_FDS
{
char cmsgbuf[CMSG_SPACE(sizeof(int) * MAX_FDS)];
union fd_pass cmsgbuf;
struct msghdr msg = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_iov = buf,
.msg_iovlen = size,
.msg_control = cmsgbuf,
.msg_control = cmsgbuf.buf,
.msg_controllen = CMSG_LEN(MAX_FDS * sizeof(int))
};
@@ -2308,7 +2308,7 @@ TRANS(SocketWritev) (XtransConnInfo ciptr, struct iovec *buf, int size)
#if XTRANS_SEND_FDS
if (ciptr->send_fds)
{
char cmsgbuf[CMSG_SPACE(sizeof(int) * MAX_FDS)];
union fd_pass cmsgbuf;
int nfd = nFd(&ciptr->send_fds);
struct _XtransConnFd *cf = ciptr->send_fds;
struct msghdr msg = {
@@ -2316,7 +2316,7 @@ TRANS(SocketWritev) (XtransConnInfo ciptr, struct iovec *buf, int size)
.msg_namelen = 0,
.msg_iov = buf,
.msg_iovlen = size,
.msg_control = cmsgbuf,
.msg_control = cmsgbuf.buf,
.msg_controllen = CMSG_LEN(nfd * sizeof(int))
};
struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg);