static void bprm_fill_uid(struct linux_binprm *bprm)
{
	struct inode *inode;
	unsigned int mode;
	kuid_t uid;
	kgid_t gid;

	/* clear any previous set[ug]id data from a previous binary */
	bprm->cred->euid = current_euid();
	bprm->cred->egid = current_egid();

	if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
		return;

	if (task_no_new_privs(current))
		return;

	inode = file_inode(bprm->file);
	mode = READ_ONCE(inode->i_mode);
	if (!(mode & (S_ISUID|S_ISGID)))
		return;

	/* Be careful if suid/sgid is set */
	mutex_lock(&inode->i_mutex);

	/* reload atomically mode/uid/gid now that lock held */
	mode = inode->i_mode;
	uid = inode->i_uid;
	gid = inode->i_gid;
	mutex_unlock(&inode->i_mutex);

	/* We ignore suid/sgid if there are no mappings for them in the ns */
	if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
		 !kgid_has_mapping(bprm->cred->user_ns, gid))
		return;

	if (mode & S_ISUID) {
		bprm->per_clear |= PER_CLEAR_ON_SETID;
		bprm->cred->euid = uid;
	}

	if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
		bprm->per_clear |= PER_CLEAR_ON_SETID;
		bprm->cred->egid = gid;
	}
}
The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.