On Fri, Dec 04, 2015 at 08:03:47PM +0100, Dmitry Vyukov wrote: > > is it with some random seccomp program? > > If normal libseccomp generates such programs than it needs to be fixed. > > Yes, it is with completely random seccomp program. > > >> Such shifts have undefined behavior according to C standard and behave > >> differently on different archs. I guess we don't want to rely on any > >> kind of undefined behavior in bpf/seccomp. And generally want to > >> completely define results of all operations in bpf. > > > > bpf is an engine and we're not going to slow down each shift operation > > by extra run-time checks or masks. > > In other words bpf shift instruction == shift in C. Both undefined > > with for large operands. > > If seccomp is relying on undefined behavior, it should be fixed. > > But note that it is not that result of such operation is undefined, it > is overall kernel behavior that becomes undefined.
not true. just don't generate random bpf programs with such shifts. kernel is fine. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
