Re: [PATCH v3] kdb: Replace deprecated strcpy() with strscpy() and memcpy()

[Daniel Thompson <daniel@riscstar.com>]

On Fri, Aug 15, 2025 at 01:28:01PM +0200, Thorsten Blum wrote:
> Hi Daniel,
>
> > On 15. Aug 2025, at 10:57, Daniel Thompson wrote:
> > Sorry but a strscpy() where the length of the destination buffer has
> > been calculated from the source string is way too much of a red flag
> > for me.
> >
> > Put another way if there are "no functional changes intended" then there
> > cannot possibly be any security benefit from replacing the "unsafe"
> > strcpy() with the "safe" strscpy(). Likewise abusing the destination
> > length argument to truncate a string makes the code shorter but *not*
> > clearer because it's too easy to misread.
>
> Deliberately truncating the source using strscpy() is a valid use case.
> strscpy() allows the size argument to be smaller than the destination
> buffer, so this is an intended use of the size argument, not an abuse.

Sorry, I didn't phrase that especially well. I regard the abuse to be
deriving the length of the destination buffer exclusively from the
state of the source buffer.

As mentioned, it would be much cleaner to eliminate the string copy entirely
than to translate it into something so similar to the original strcpy().


Daniel.