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 arithmetic.

So, clarify the preferred way in these cases.

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Len Baker <len.baker@gmx.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20210925143455.21221-1-len.baker@gmx.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 8ced754a5a0f65fad5b2c2a42753488d120c697b..388cb19f5dbb6e4f24ecabe947fb482fdfe6ae07 100644 (file)
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -59,8 +59,9 @@ risk of them overflowing. This could lead to values wrapping around and a
 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.)
+can warn if they might overflow. However, the preferred way in these
+cases is to refactor the code as suggested below to avoid the open-coded
+arithmetic.)
 
 For example, do not use ``count * size`` as an argument, as in::