Commit 12e130b0 authored Oct 22, 2012 by David Howells Committed by Rusty Russell Dec 05, 2012

MODSIGN: Don't use enum-type bitfields in module signature info block



Don't use enum-type bitfields in the module signature info block as we can't be
certain how the compiler will handle them.  As I understand it, it is arch
dependent, and it is possible for the compiler to rearrange them based on
endianness and to insert a byte of padding to pad the three enums out to four
bytes.

Instead use u8 fields for these, which the compiler should emit in the right
order without padding.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

parent df2fc246

kernel/module_signing.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -27,9 +27,9 @@
		* - Information block
		*/
		struct module_signature {
		enum pkey_algo algo : 8; /* Public-key crypto algorithm */
		enum pkey_hash_algo hash : 8; /* Digest algorithm */
		enum pkey_id_type id_type : 8; /* Key identifier type */
		u8 algo; /* Public-key crypto algorithm [enum pkey_algo] */
		u8 hash; /* Digest algorithm [enum pkey_hash_algo] */
		u8 id_type; /* Key identifier type [enum pkey_id_type] */
		u8 signer_len; /* Length of signer's name */
		u8 key_id_len; /* Length of key identifier */
		u8 __pad[3];