On 17/05/2022 09:51, Arnaud Panaïotis wrote:

Hello,

I'm working for a client to generate embedded 32-bits Linux Kernel working after y2038 issue.

I generated a 5.15 Kernel thought Buildroot with Coreutils 9.0, GCC 11.2.0, Binutils 2.37, Glibc 2.34-9 and CFLAGS -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64.

I encounter an issue while working with OpenSSH (I initially contacted them before).

To clarify: did you build just openssh with -D_TIME_BITS=64, or did you build the user space this way?

After 2038, /usr/sbin/sshd does not create an error but it child does generate this one: daemon() failed: Value too large for defined data type

This happend here in sshd.c:

2019 /* 2020 * If not in debugging mode, not started from inetd and not already 2021 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 2022 * terminal, and fork. The original process exits. 2023 */ 2024 already_daemon = daemonized(); 2025 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 2026 2027 if (daemon(0, 0) == -1) 2028 fatal("daemon() failed: %.200s", strerror(errno));

My guess is that there are parts of glibc that are not fully y2038-safe at the moment, but merely provide the interfaces for time64 applications.

In the glibc code, I see

int daemon (int nochdir, int noclose) { ... if ((fd = __open_nocancel(_PATH_DEVNULL, O_RDWR, 0)) != -1 && (__builtin_expect (__fstat64 (fd, &st), 0) == 0)) { ... } else { __close_nocancel_nostatus (fd); return -1; } return (0); }

__fstatat64 (int fd, const char *file, struct stat64 *buf, int flags) { struct __stat64_t64 st_t64; return __fstatat64_time64 (fd, file, &st_t64, flags) ?: __cp_stat64_t64_stat64 (&st_t64, buf); }

If I'm reading this correctly, daemon() internally uses the time32 version of 'stat', which fails for files with out-of-range timestamps. Are you able to rebuild the ssh binary (or your entire distro, if that's easier) against musl-1.2.x instead of glibc to see if the same thing happens there?

Arnd

To reproduce:

# date -s "2040-05-12" # hwclock --systohc # reboot # /usr/sbin/sshd

Note this error occurs only after the reboot, and setting a date before 2038 also require a reboot to remove the error.

strace and gdb trace linked.

Let me know if you need additional information.