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stddef.h: Introduce sizeof_field() 

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>
hifive-unleashed-5.1
Kees Cook 2018-01-10 12:53:20 -08:00
parent c758868624
commit 4229a47017
1 changed files with 9 additions and 1 deletions
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10
include/linux/stddef.h
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@ -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