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-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 01/16] docs: deprecated.rst: Add uninitialized_var()
Date: Fri, 19 Jun 2020 20:29:52 -0700 [thread overview]
Message-ID: <20200620033007.1444705-2-keescook@chromium.org> (raw)
In-Reply-To: <20200620033007.1444705-1-keescook@chromium.org>
Nothing should be using this macro, and the entire idea of tricking the
compiler into silencing such warnings is a mistake.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
Documentation/process/deprecated.rst | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 652e2aa02a66..943a926ecbbb 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -51,6 +51,24 @@ to make sure their systems do not continue running in the face of
"unreachable" conditions. (For example, see commits like `this one
<https://git.kernel.org/linus/d4689846881d160a4d12a514e991a740bcb5d65a>`_.)
+uninitialized_var()
+-------------------
+For any compiler warnings about uninitialized variables, just add
+an initializer. Using the uninitialized_var() macro (or similar
+warning-silencing tricks) is dangerous as it papers over `real bugs
+<https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/>`_
+(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. Keep in
+mind that in most cases, if an initialization is obviously redundant,
+the compiler's dead-store elimination pass will make sure there are no
+needless variable writes.
+
+As Linus has said, this macro
+`must <https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/>`_
+`be <https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/>`_
+`removed <https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/>`_.
+
open-coded arithmetic in allocator arguments
--------------------------------------------
Dynamic size calculations (especially multiplication) should not be
--
2.25.1
next prev parent reply other threads:[~2020-06-20 3:30 UTC|newest]
Thread overview: 63+ 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 ` Kees Cook [this message]
2020-06-22 16:59 ` [PATCH v2 01/16] docs: deprecated.rst: Add uninitialized_var() Nick Desaulniers
2020-06-22 16:59 ` Nick Desaulniers
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 17:04 ` Nick Desaulniers
2020-06-22 17:04 ` Nick Desaulniers
2020-06-22 21:04 ` Kees Cook
2020-06-22 21:04 ` Kees Cook
2020-06-23 18:29 ` Nick Desaulniers
2020-06-23 18:29 ` Nick Desaulniers
2020-06-23 18:29 ` Nick Desaulniers
2020-07-15 10:37 ` Kalle Valo
2020-07-15 10:37 ` Kalle Valo
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
2020-06-22 9:03 ` Stephen Boyd
2020-06-20 3:29 ` [PATCH v2 08/16] spi: davinci: " Kees Cook
2020-07-01 20:39 ` Mark Brown
2020-07-01 20:39 ` Mark Brown
2020-07-02 15:21 ` Kees Cook
2020-07-02 15:21 ` Kees Cook
2020-07-02 15:23 ` Mark Brown
2020-07-02 15:23 ` Mark Brown
2020-07-02 15:42 ` Kees Cook
2020-07-02 15:42 ` Kees Cook
2020-07-02 16:23 ` Joe Perches
2020-07-02 16:23 ` Joe Perches
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
2020-06-22 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
2020-06-22 17:22 ` Nick Desaulniers
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
2020-06-22 18:39 ` Nick Desaulniers
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 ` [PATCH v2 15/16] treewide: Remove uninitialized_var() usage Kees Cook
2020-06-22 11:32 ` Dan Carpenter
2020-06-22 11:32 ` Dan Carpenter
2020-06-20 3:30 ` [PATCH v2 16/16] compiler: Remove uninitialized_var() macro Kees Cook
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
2020-06-22 17:27 ` Nick Desaulniers
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 7:03 ` Sedat Dilek
2020-06-20 15:57 ` Kees Cook
2020-06-22 9:07 ` Sedat Dilek
2020-06-22 9:07 ` Sedat Dilek
2020-06-22 9:07 ` Sedat Dilek
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=20200620033007.1444705-2-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-doc@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.