Bug 2011602

In

https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/tree/misc-utils/logger.c?h=stable%2Fv2.32#n963

we see:

	size_t max_usrmsg_size = ctl->max_message_size - strlen(ctl->hdr);
	char *const buf = xmalloc(max_usrmsg_size + 2 + 2);

since ctl->max_message_size defaults to 1024, unless the -S option is used,
a very long message will result in a very large unsigned value, causing
the malloc call to fail.

User suggests pseudo patch:

-	size_t max_usrmsg_size = ctl->max_message_size - strlen(ctl->hdr);
+	size_t usrmsg_size = strlen(ctl->hdr);
+	size_t max_usrmsg_size = (ctl->max_message_size < usrmgr_size) ? usrmgr_size : ctl->max_message_size);

  Need a careful review of the code, as a few lines below there is also:

				max_usrmsg_size =
				    ctl->max_message_size - strlen(ctl->hdr);

what again might write out of bounds due to negative value as unsigned.