error: format not a string literal and no format arguments

[Cristian Ionescu-Idbohrn]

On Fri, 23 Oct 2009, Denys Vlasenko wrote:

> We KNOW bb_path_mtab_file does not contain %format.
> I do not want to vandalize code just because specific version of gcc
> is nuts.

Sorry, I was neither involved in the development of that specific gcc
option nor in gentoo's (and several other distributions) making
-Wformat-security a default option.  Of course, the current behaviour
could be reverted to not being default with a -Wno-format-security in
Makefile.flags.  Mike Frysinger wrote about it a while ago:

	http://patchwork.kernel.org/patch/4730/

Still, do we want to do that?

There are some obvious places that would be ok, as we control the strings:

	bb_error_msg(bb_msg_memory_exhausted);
	bb_error_msg(bb_msg_perm_denied_are_you_root);
	bb_error_msg_and_die(bb_msg_memory_exhausted);
	bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);
	bb_error_msg_and_die(bb_msg_read_error);
	bb_error_msg_and_die(bb_msg_write_error);
	bb_perror_msg(bb_msg_can_not_create_raw_socket);
	bb_perror_msg(bb_msg_read_error);
	bb_perror_msg(bb_msg_write_error);
	bb_perror_msg(bb_path_mtab_file);
	bb_perror_msg_and_die(bb_msg_can_not_create_raw_socket);
	bb_perror_msg_and_die(bb_msg_read_error);
	bb_perror_msg_and_die(bb_msg_standard_input);
	bb_perror_msg_and_die(bb_msg_standard_output);
	bb_perror_msg_and_die(bb_path_mtab_file);
	col = fmtstr(s, 32, strsignal(st));
	printf(bbconfig_config);

and some other places where it might not:

	bb_error_msg((char*)error_pkt_str);
	bb_perror_msg(file);
	bb_perror_msg_and_die(str);
	printf(pr->fmt);

Anyway, making -Wformat-security a default option is, arguably, for a
reason.  A lot has been written about it in the passed 10 years or so.
Try:

	http://en.wikipedia.org/wiki/Format_string_attack

which refers to this:

	http://julianor.tripod.com/bc/formatstring-1.2.pdf

> Does it compile with CONFIG_WERROR off?

Yes (forgot about that).

Found another small bug.  This:

--- util-linux/mkfs_ext2.c.orig	2009-10-22 00:55:55.000000000 +0200
+++ util-linux/mkfs_ext2.c	2009-10-24 10:45:15.370943859 +0200
@@ -389,7 +389,7 @@ int mkfs_ext2_main(int argc UNUSED_PARAM
 		"%u inodes, %u blocks\n"
 		"%u blocks (%u%%) reserved for the super user\n"
 		"First data block=%u\n"
-		"Maximum filesystem blocks=%u\n"
+		"Maximum filesystem blocks=%lu\n"
 		"%u block groups\n"
 		"%u blocks per group, %u fragments per group\n"
 		"%u inodes per group"

corrects this:

util-linux/mkfs_ext2.c: In function 'mkfs_ext2_main':
util-linux/mkfs_ext2.c:406: error: format '%u' expects type 'unsigned int',
but argument 12 has type 'long unsigned int'


Cheers,

-- 
Cristian