task_struct: only use anon struct under randstruct plugin
authorKees Cook <keescook@chromium.org>
Tue, 10 Apr 2018 23:32:44 +0000 (16:32 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 11 Apr 2018 17:28:35 +0000 (10:28 -0700)
commit2cfe0d3009418a132b93d78642a8059a38fe5944
treebe663132e62f3c0bffff1db9b13ee895b2ce6707
parentd4ef8d3ff005c70f6c9e2ffea14cc65fc8fe328d
task_struct: only use anon struct under randstruct plugin

The original intent for always adding the anonymous struct in
task_struct was to make sure we had compiler coverage.

However, this caused pathological padding of 40 bytes at the start of
task_struct.  Instead, move the anonymous struct to being only used when
struct layout randomization is enabled.

Link: http://lkml.kernel.org/r/20180327213609.GA2964@beast
Fixes: 29e48ce87f1e ("task_struct: Allow randomized")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/compiler-clang.h
include/linux/compiler-gcc.h