I started getting warnings for this one file, though I can't see what changed
since it was originally introduced in commit
fec7b6690541 ("samples: add an
example of seccomp user trap").
samples/seccomp/user-trap.c: In function 'send_fd':
samples/seccomp/user-trap.c:50:11: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
50 | *((int *)CMSG_DATA(cmsg)) = fd;
| ~^~~~~~~~~~~~~~~~~~~~~~~
samples/seccomp/user-trap.c: In function 'recv_fd':
samples/seccomp/user-trap.c:83:18: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
83 | return *((int *)CMSG_DATA(cmsg));
| ~^~~~~~~~~~~~~~~~~~~~~~~
Using a temporary pointer variable avoids the warning.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20240212111737.917428-1-arnd@kernel.org
Acked-by: Tycho Andersen <tandersen@netflix.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
{
struct msghdr msg = {};
struct cmsghdr *cmsg;
+ int *fd_ptr;
char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
struct iovec io = {
.iov_base = &c,
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
- *((int *)CMSG_DATA(cmsg)) = fd;
+ fd_ptr = (int *)CMSG_DATA(cmsg);
+ *fd_ptr = fd;
msg.msg_controllen = cmsg->cmsg_len;
if (sendmsg(sock, &msg, 0) < 0) {
{
struct msghdr msg = {};
struct cmsghdr *cmsg;
+ int *fd_ptr;
char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
struct iovec io = {
.iov_base = &c,
}
cmsg = CMSG_FIRSTHDR(&msg);
+ fd_ptr = (int *)CMSG_DATA(cmsg);
- return *((int *)CMSG_DATA(cmsg));
+ return *fd_ptr;
}
static int user_trap_syscall(int nr, unsigned int flags)