[PATCH] btf: Protect BTF_KIND_INFO against invalid kind

[Will Hawkins <hawkinsw@obs.cr>]

If the user provides a kind value that is more than 5 bits, the
BTF_KIND_INFO macro would emit incorrect values for info (by clobbering
values of the kind flag).

Tested on x86_64-redhat-linux.

include/ChangeLog:

	* btf.h (BTF_TYPE_INFO): Protect against user providing invalid
	  kind.

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
---

Notes:
     I have a small out-of-tree test but was not sure whether a) it should
		 be included and/or b) where it should be included. If you would
		 like me to include it, please just let me know where it should go!

 include/btf.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/btf.h b/include/btf.h
index 3f45ffb0b6b..0c3e1a1cf51 100644
--- a/include/btf.h
+++ b/include/btf.h
@@ -82,7 +82,7 @@ struct btf_type
   };
 };
 
-/* The folloing macros access the information encoded in btf_type.info.  */
+/* The following macros access the information encoded in btf_type.info.  */
 /* Type kind. See below.  */
 #define BTF_INFO_KIND(info)	(((info) >> 24) & 0x1f)
 /* Number of entries of variable length data following certain type kinds.
@@ -95,7 +95,7 @@ struct btf_type
 
 /* Encoding for struct btf_type.info.  */
 #define BTF_TYPE_INFO(kind, kflag, vlen) \
-  ((((kflag) ? 1 : 0 ) << 31) | ((kind) << 24) | ((vlen) & 0xffff))
+  ((((kflag) ? 1 : 0 ) << 31) | ((kind & 0x1f) << 24) | ((vlen) & 0xffff))
 
 #define BTF_KIND_UNKN		0	/* Unknown or invalid.  */
 #define BTF_KIND_INT		1	/* Integer.  */
-- 
2.45.2