Re: [PATCH v2] docs: deprecated.rst: Clarify open-coded arithmetic with literals
From: Jonathan Corbet <corbet@lwn.net>
Date: 2021-09-14 21:07:03
Also in:
linux-hardening, lkml
Len Baker [off-list ref] writes:
quoted hunk ↗ jump to hunk
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 <redacted> Signed-off-by: Len Baker <redacted> --- Changelog v1 -> v2 - Clarify the sentence by changing "keep <foo> out" with "avoid <foo>" (Joe Perches). 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..b5a8be914178 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 avoid the open-coded math idiom.)
Sorry for being so slow to get to this... honestly, though, I've been staring at it for a bit and cannot figure out what you are trying to communicate. What does "math idiom" mean here? If you are trying to say that using literals is *not* harmless, then perhaps the first part of the parenthetical should be taken out? Confused... jon