[PATCH] i386 / desc_empty macro is incorrect

Chuck Ebbert noticed that the desc_empty macro is incorrect. Fix it.

Thankfully, this is not used as a security check, but it can falsely
overwrite TLS segments with carefully chosen base / limits. I do not
believe this is an issue in practice, but it is a kernel bug.

Signed-off-by: Zachary Amsden <[e-mail]>
Signed-off-by: Chris Wright <[e-mail]>

[ x86-64 had the same problem, and the same fix. Linus ]

Signed-off-by: Linus Torvalds <[e-mail]>

include/asm-i386/processor.h

···
 };
 
 #define desc_empty(desc) \
-		(!((desc)->a + (desc)->b))
+		(!((desc)->a | (desc)->b))
 
 #define desc_equal(desc1, desc2) \
 		(((desc1)->a == (desc2)->a) && ((desc1)->b == (desc2)->b))

include/asm-x86_64/processor.h

···
 #define ID_MASK		0x00200000
 
 #define desc_empty(desc) \
-               (!((desc)->a + (desc)->b))
+               (!((desc)->a | (desc)->b))
 
 #define desc_equal(desc1, desc2) \
                (((desc1)->a == (desc2)->a) && ((desc1)->b == (desc2)->b))