[PATCH] audit: do a quick exit when syscall number is invalid

[CGEL]

On Mon, Mar 28, 2022 at 11:06:12PM -0400, Paul Moore wrote:
> On Mon, Mar 28, 2022 at 9:48 PM CGEL <cgel.zte at gmail.com> wrote:
> > Sorry could anybody give a hand to solve this? It works well on x86_64 and arm64.
> > I have no alpha environment and not familiar to this arch, much thanks!
> 
> Regardless of if this is fixed, I'm not convinced this is something we
> want to merge.  After all, a process executed a syscall and we should
> process it like any other; just because it happens to be an
> unrecognized syscall on a particular kernel build doesn't mean it
> isn't security relevant (probing for specific syscall numbers may be a
> useful attack fingerprint).
>
Thanks for your reply.

But syscall number less than 0 is even invalid for auditctl. So we
will never hit this kind of audit rule. And invalid syscall number
will always cause failure early in syscall handle.

sh-4.2# auditctl -a always,exit -F arch=b64 -S -1
Syscall name unknown: -1

> -- 
> paul-moore.com