linux-hardening - [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals

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Message-Id: <20210827171226.2938-1-len.baker@gmx.com>
Date:   Fri, 27 Aug 2021 19:12:26 +0200
From:   Len Baker <len.baker@....com>
To:     Jonathan Corbet <corbet@....net>, Kees Cook <keescook@...omium.org>
Cc:     Len Baker <len.baker@....com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Joe Perches <joe@...ches.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals

Although using literals for size calculation in allocator arguments may
be harmless due to compiler warnings in case of overflows, it is better
to refactor the code to avoid the use of open-coded math idiom.

So, clarify the preferred way in these cases.

Suggested-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Len Baker <len.baker@....com>
---
 Documentation/process/deprecated.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 9d83b8db8874..fdfafdefe296 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -60,7 +60,8 @@ smaller allocation being made than the caller was expecting. Using those
 allocations could lead to linear overflows of heap memory and other
 misbehaviors. (One exception to this is literal values where the compiler
 can warn if they might overflow. Though using literals for arguments as
-suggested below is also harmless.)
+suggested below is also harmless. So, the preferred way in these cases is
+to refactor the code to keep the open-coded math idiom out.)

 For example, do not use ``count * size`` as an argument, as in::

--
2.25.1