Re: [PATCH net-next v3] net: Replace %pK output with 0

[Kees Cook <kees@kernel.org>]

On Wed, Aug 12, 2026 at 01:05:31PM +0200, Sebastian Andrzej Siewior wrote:
> Commit 71338aa7d050c ("net: convert %p usage to %pK") which is from
> 2011 and changed the %p annotation for pointer to %pK. Back then the
> default behaviour for %p was to print the pointer. The %pK modifier was
> introduced to able to control the behaviour of specific pointer values
> without changing the behaviour of %p for everyone. It was dedicated to
> avoid leaking pointers via /proc.
> 
> There was also the idea to remove the check from formatting the string
> and move to the open callback with some helpers but this did not happen.
> 
> Things changed over time. The default behaviour for %p is now to print a
> hash pointer which does not leak the address but allows to correlate if
> two pointers are equal.
> The policy on %p is to not introduce new ones. This is somehow in
> between since it already exists. The pointer are usually socket pointers
> and I don't see any value in exposing them. Therefore I am following the
> recommendation of removing them. Since their usage in /proc/ can be
> considered ABI I replace the pointer with a 0.
> 
> Replace the %pK annotation with 0 value. Correct the spacing for the
> cases where pointer is at the beginning. Use %ps in CAN where the read
> callback is used.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

I love this kind of replacement. :)

Reviewed-by: Kees Cook <kees@kernel.org>

-- 
Kees Cook