On Fri, Mar 18, 2022 at 09:44:30AM -0500, Eric W. Biederman wrote: > Kees Cook <keescook@xxxxxxxxxxxx> writes: > > > On Tue, Mar 15, 2022 at 06:21:08PM -0500, Eric W. Biederman wrote: > >> > >> Today ptrace_message is easy to overlook as it not a core part of > >> ptrace_stop. It has been overlooked so much that there are places > >> that set ptrace_message and don't clear it, and places that never set > >> it. So if you get an unlucky sequence of events the ptracer may be > >> able to read a ptrace_message that does not apply to the current > >> ptrace stop. > >> > >> Move setting of ptrace_message into ptrace_stop so that it always gets > >> set before the stop, and always gets cleared after the stop. This > >> prevents non-sense from being reported to userspace and makes > >> ptrace_message more visible in the ptrace helper functions so that > >> kernel developers can see it. > >> > >> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> > > > > This looks good to me. Did you happen to run the seccomp selftests > > before/after these changes? > > I did not. This is a pure ptrace change. Do you see a way that seccomp > could be involved? Sorry, that wasn't clear: seccomp includes a number of ptrace tests as well, especially involving handling process death, messages, and signals. I'll give it a spin; so far it seems fine. -- Kees Cook
