From: Kees Cook <keescook@chromium.org>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Alexander Potapenko <glider@google.com>,
Joe Perches <joe@perches.com>, Andy Whitcroft <apw@canonical.com>,
x86@kernel.org, drbd-dev@lists.linbit.com,
linux-block@vger.kernel.org, b43-dev@lists.infradead.org,
netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
linux-ide@vger.kernel.org, linux-clk@vger.kernel.org,
linux-spi@vger.kernel.org, linux-mm@kvack.org,
clang-built-linux@googlegroups.com
Subject: [PATCH 10/10] compiler: Remove uninitialized_var() macro
Date: Wed, 3 Jun 2020 16:32:03 -0700 [thread overview]
Message-ID: <20200603233203.1695403-11-keescook@chromium.org> (raw)
In-Reply-To: <20200603233203.1695403-1-keescook@chromium.org>
Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.
As recommended[2] by[3] Linus[4], remove the macro.
[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
include/linux/compiler-clang.h | 2 --
include/linux/compiler-gcc.h | 6 ------
tools/include/linux/compiler.h | 2 --
tools/virtio/linux/kernel.h | 2 --
4 files changed, 12 deletions(-)
diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index 790c0c6b8552..019f444b500b 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -5,8 +5,6 @@
/* Compiler specific definitions for Clang compiler */
-#define uninitialized_var(x) x = *(&(x))
-
/* same as gcc, this was present in clang-2.6 so we can assume it works
* with any version that can compile the kernel
*/
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index d7ee4c6bad48..ac3e29ae32de 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -58,12 +58,6 @@
(typeof(ptr)) (__ptr + (off)); \
})
-/*
- * A trick to suppress uninitialized variable warning without generating any
- * code
- */
-#define uninitialized_var(x) x = x
-
#ifdef CONFIG_RETPOLINE
#define __noretpoline __attribute__((__indirect_branch__("keep")))
#endif
diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 180f7714a5f1..29cbb73f2ae0 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -108,8 +108,6 @@
# define noinline
#endif
-#define uninitialized_var(x) x = *(&(x))
-
#include <linux/types.h>
/*
diff --git a/tools/virtio/linux/kernel.h b/tools/virtio/linux/kernel.h
index 6683b4a70b05..1e14ab967c11 100644
--- a/tools/virtio/linux/kernel.h
+++ b/tools/virtio/linux/kernel.h
@@ -109,8 +109,6 @@ static inline void free_page(unsigned long addr)
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
-#define uninitialized_var(x) x = x
-
# ifndef likely
# define likely(x) (__builtin_expect(!!(x), 1))
# endif
--
2.25.1
next prev parent reply other threads:[~2020-06-03 23:33 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-03 23:31 [PATCH 00/10] Remove uninitialized_var() macro Kees Cook
2020-06-03 23:31 ` [PATCH 01/10] x86/mm/numa: Remove uninitialized_var() usage Kees Cook
2020-06-04 7:58 ` Thomas Gleixner
2020-06-04 11:41 ` Miguel Ojeda
2020-06-04 14:56 ` Kees Cook
2020-06-04 15:22 ` Miguel Ojeda
2020-06-04 14:34 ` Kees Cook
2020-06-04 21:39 ` Thomas Gleixner
2020-06-04 22:39 ` Kees Cook
2020-06-03 23:31 ` [PATCH 02/10] drbd: " Kees Cook
2020-06-04 19:56 ` Nick Desaulniers
2020-06-03 23:31 ` [PATCH 03/10] b43: " Kees Cook
2020-06-04 20:08 ` Nick Desaulniers
2020-06-04 20:18 ` Kees Cook
2020-06-04 20:25 ` Nick Desaulniers
2020-06-05 9:20 ` Kalle Valo
2020-06-03 23:31 ` [PATCH 04/10] rtlwifi: rtl8192cu: " Kees Cook
2020-06-04 20:16 ` Nick Desaulniers
2020-06-05 9:18 ` Kalle Valo
2020-06-03 23:31 ` [PATCH 05/10] ide: " Kees Cook
2020-06-04 19:29 ` Nick Desaulniers
2020-06-04 20:20 ` Kees Cook
2020-06-04 20:29 ` Nick Desaulniers
2020-06-15 19:32 ` Kees Cook
2020-06-04 20:58 ` Sedat Dilek
2020-06-03 23:31 ` [PATCH 06/10] clk: st: " Kees Cook
2020-06-04 4:38 ` Stephen Boyd
2020-06-03 23:32 ` [PATCH 07/10] spi: davinci: " Kees Cook
2020-06-04 19:40 ` Nick Desaulniers
2020-06-03 23:32 ` [PATCH 08/10] checkpatch: Remove awareness of uninitialized_var() macro Kees Cook
2020-06-04 0:02 ` Joe Perches
2020-06-04 1:40 ` Kees Cook
2020-06-04 1:47 ` Joe Perches
2020-06-04 2:44 ` Kees Cook
2020-06-04 2:53 ` Sedat Dilek
2020-06-04 3:46 ` Kees Cook
2020-06-03 23:32 ` [PATCH 09/10] treewide: Remove uninitialized_var() usage Kees Cook
2020-06-04 3:33 ` Nathan Chancellor
2020-06-04 4:02 ` Kees Cook
2020-06-04 10:45 ` Leon Romanovsky
2020-06-04 13:23 ` Jason Gunthorpe
2020-06-04 14:59 ` Kees Cook
2020-06-04 17:57 ` Jason Gunthorpe
2020-06-04 19:09 ` Geert Uytterhoeven
2020-06-05 9:25 ` Kalle Valo
2020-06-03 23:32 ` Kees Cook [this message]
2020-06-04 0:00 ` [PATCH 10/10] compiler: Remove uninitialized_var() macro Bart Van Assche
2020-06-04 0:50 ` Miguel Ojeda
2020-06-04 1:23 ` [PATCH 00/10] " Sedat Dilek
2020-06-04 1:44 ` Kees Cook
2020-06-04 1:46 ` Sedat Dilek
2020-06-04 3:33 ` Nathan Chancellor
2020-06-04 7:26 ` Sedat Dilek
2020-06-04 14:27 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200603233203.1695403-11-keescook@chromium.org \
--to=keescook@chromium.org \
--cc=apw@canonical.com \
--cc=b43-dev@lists.infradead.org \
--cc=clang-built-linux@googlegroups.com \
--cc=drbd-dev@lists.linbit.com \
--cc=glider@google.com \
--cc=joe@perches.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-clk@vger.kernel.org \
--cc=linux-ide@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-spi@vger.kernel.org \
--cc=linux-wireless@vger.kernel.org \
--cc=miguel.ojeda.sandonis@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).