On Mon, Nov 27, 2017 at 04:52:21PM -0800, Kees Cook wrote: > On Mon, Nov 27, 2017 at 2:30 PM, Tobin C. Harding <m...@tobin.cc> wrote: > > This is an RFC for two reasons. > > > > 1) I don't know who this patch set may break? > > 2) Patch set includes a function that is not called. Function is there > > to facilitate fixing breakages. > > > > _If_ no one gets broken then we can remove the unused function. > > > > Thanks for looking at this. > > > > Currently if a pointer is printed using %p[ssB] and the symbol is not > > found (kallsyms_lookup() fails) then we print the actual address. This > > potentially leaks kernel addresses. We could instead print something > > _safe_. If kallsyms is made to return an error then callers of > > sprint_symbol() can decide what to do. > > > > In the case of vsprintf we can print '<no-symbol>' (patch 2). > > > > In the case of trace we want the address so we can check the return code > > and print the address if no symbol is found (patch 3). > > > > Design for this set loosely suggested by Steve Rostedt (so as not to > > break ftrace). > > If tracing is the only place this is needed, this series seems reasonable to > me.
Noob question: how do we _know_ this. In other words how do we know no userland tools rely on the current behaviour? No stress to answer Kees, this is a pretty general kernel dev question. thanks, Tobin.