Re: [PATCH] apparmor: aa_buffer: Convert 1-element array to flexible array

[Kees Cook]

On Thu, May 11, 2023 at 02:48:29PM -0700, John Johansen wrote:
> On 5/11/23 14:34, Kees Cook wrote:
> > In the ongoing effort to convert all fake flexible arrays to proper
> > flexible arrays, replace aa_buffer's 1-element "buffer" member with a
> > flexible array.
> > 
> > Cc: John Johansen <john.johansen@xxxxxxxxxxxxx>
> > Cc: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
> > Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
> > Cc: James Morris <jmorris@xxxxxxxxx>
> > Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx>
> > Cc: apparmor@xxxxxxxxxxxxxxxx
> > Cc: linux-security-module@xxxxxxxxxxxxxxx
> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> 
> Acked-by: John Johansen <john.johansen@xxxxxxxxxxxxx>
> 
> I have pulled this into my tree.

Thanks!

> 
> > ---
> > One thing I notice here is that it may be rare for "buffer" to ever change
> > for a given kernel. Could this just be made PATH_MAX * 2 directly and
> > remove the module parameter, etc, etc?
> 
> possibly. Currently the only use case I know of is for some stress testing
> where we drop the buffer size down really small to try and break things.
> This isn't part of the regular regression runs and could be handle with a
> config/compile time to a buffer size constant.

Okay, cool. I figured the conversion to fixed-size is sort of nice, but
it probably won't be of much use as-is since it's the buffer, not the
aa_buffer, is passed around. The compiler would still not have any idea
what the bounds are. :)

-- 
Kees Cook