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+++ This bug was initially created as a clone of Bug #2141685 +++

In order to call SHM_STAT_ANY kernel operations through shmctl on older glibc, it was necessary to pass SHM_STAT_ANY | IPC_64 in the command argument, otherwise the ipc system call would be invoked without the IPC_64 flag, giving unexpected results on powerpc64le-linux-gnu at least.

Current glibc no longer supports that because it checks the command argument for validity without masking the IPC_64 bit.

The backport for bug 1912670 contains a list of accepted shmctl commands, and that does not include SHM_STAT_ANY | IPC_64 either, so the issue is present in current RHEL 8.8 glibc as well.

The RHEL 8.8 backport is buggy.  The EINVAL check failure is never reported to the caller:

int
__new_shmctl (int shmid, int cmd, struct shmid_ds *buf)
{
  switch (cmd)
    {
    case IPC_RMID:
    case SHM_LOCK:
    case SHM_UNLOCK:
    case IPC_SET:
    case IPC_STAT:
    case SHM_STAT:
    case SHM_STAT_ANY:
    case IPC_INFO:
    case SHM_INFO:
      break;
    default:
      __set_errno (EINVAL);
      break;
    }
#ifdef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
  return INLINE_SYSCALL_CALL (shmctl, shmid, cmd | __IPC_64, buf);
#else
  return INLINE_SYSCALL_CALL (ipc, IPCOP_shmctl, shmid, cmd | __IPC_64, 0,
			      buf);
#endif
}

There's no “return -1;”, so the check failure is hidden from the caller. We should still clean this up and remove the switch statement (to match upstream).

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (glibc bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:2955