From: Kees Cook <keescook@chromium.org>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Bart van Assche <bvanassche@acm.org>,
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Sedat Dilek <sedat.dilek@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-doc@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 v2 16/16] compiler: Remove uninitialized_var() macro
Date: Fri, 19 Jun 2020 20:30:06 -0700 [thread overview]
Message-ID: <20200620033007.1444705-16-keescook@chromium.org> (raw)
In-Reply-To: <20200620033007.1444705-1-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. With the recent
change to disable -Wmaybe-uninitialized in v5.7 in commit 78a5255ffb6a
("Stop the ad-hoc games with -Wno-maybe-initialized"), this is likely
the best time to make this treewide change.
[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>
Reviewed-by: Bart van Assche <bvanassche@acm.org>
Reviewed-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
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 ee37256ec8bd..f2371b83aaf2 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 7dd4e0349ef3..84e099a87383 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -59,12 +59,6 @@
(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 9f9002734e19..2f2f4082225e 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -111,8 +111,6 @@
# 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:[~2020-06-20 3:31 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-20 3:29 [PATCH v2 00/16] Remove uninitialized_var() macro Kees Cook
2020-06-20 3:29 ` [PATCH v2 01/16] docs: deprecated.rst: Add uninitialized_var() Kees Cook
2020-06-22 16:59 ` Nick Desaulniers
2020-06-20 3:29 ` [PATCH v2 02/16] x86/mm/numa: Remove uninitialized_var() usage Kees Cook
2020-06-20 3:29 ` [PATCH v2 03/16] drbd: " Kees Cook
2020-06-20 3:29 ` [PATCH v2 04/16] b43: " Kees Cook
2020-06-22 17:04 ` Nick Desaulniers
2020-06-22 21:04 ` Kees Cook
2020-06-23 18:29 ` Nick Desaulniers
2020-07-15 10:37 ` Kalle Valo
2020-06-20 3:29 ` [PATCH v2 05/16] rtlwifi: rtl8192cu: " Kees Cook
2020-06-20 3:29 ` [PATCH v2 06/16] ide: " Kees Cook
2020-06-20 3:29 ` [PATCH v2 07/16] clk: st: " Kees Cook
2020-06-22 9:03 ` Stephen Boyd
2020-06-20 3:29 ` [PATCH v2 08/16] spi: davinci: " Kees Cook
2020-07-01 20:39 ` Mark Brown
2020-07-02 15:21 ` Kees Cook
2020-07-02 15:23 ` Mark Brown
2020-07-02 15:42 ` Kees Cook
2020-07-02 16:23 ` Joe Perches
2020-06-20 3:30 ` [PATCH v2 09/16] clk: spear: " Kees Cook
2020-06-22 9:03 ` Stephen Boyd
2020-06-20 3:30 ` [PATCH v2 10/16] KVM: PPC: Book3S PR: " Kees Cook
2020-06-22 17:22 ` Nick Desaulniers
2020-06-20 3:30 ` [PATCH v2 11/16] media: sur40: " Kees Cook
2020-06-22 18:39 ` Nick Desaulniers
2020-06-20 3:30 ` [PATCH v2 12/16] f2fs: Eliminate usage of uninitialized_var() macro Kees Cook
2020-06-20 3:30 ` [PATCH v2 14/16] checkpatch: Remove awareness " Kees Cook
2020-06-20 3:30 ` Kees Cook [this message]
2020-06-20 3:30 ` [PATCH v2 13/16] mm/debug_vm_pgtable: Remove uninitialized_var() usage Kees Cook
2020-06-22 17:27 ` Nick Desaulniers
2020-06-20 7:03 ` [PATCH v2 00/16] Remove uninitialized_var() macro Sedat Dilek
2020-06-20 15:57 ` Kees Cook
2020-06-22 9:07 ` Sedat Dilek
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