stddef.h: Introduce sizeof_field() (4229a470) · Commits · 戴 / test

The size of fields within a structure is needed in a few places in the kernel already, and will be needed for the usercopy whitelisting when declaring whitelist regions within structures. This creates a dedicated macro and redefines offsetofend() to use it. Existing usage, ignoring the 1200+ lustre assert uses: $ git grep -E 'sizeof$\(\((struct )?[a-zA-Z_]+ \*$0\)->' | \ grep -v staging/lustre | wc -l 65 Signed-off-by:

Kees Cook <keescook@chromium.org>

include/linux/stddef.h

+9 −1

Original line number	Diff line number	Diff line
		@@ -19,6 +19,14 @@ enum {
		#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER)
		#endif

		/**
		* sizeof_field(TYPE, MEMBER)
		*
		* @TYPE: The structure containing the field of interest
		* @MEMBER: The field to return the size of
		*/
		#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))

		/**
		* offsetofend(TYPE, MEMBER)
		*
		@@ -26,6 +34,6 @@ enum {
		* @MEMBER: The member within the structure to get the end offset of
		*/
		#define offsetofend(TYPE, MEMBER) \
		(offsetof(TYPE, MEMBER) + sizeof(((TYPE *)0)->MEMBER))
		(offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER))

		#endif

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